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Resetting iMac Firmware?

cmaus@mac.com

By cmaus@mac.com,
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cmaus@mac.com
cmaus@mac.com
Posted
Posted

Hello, I am really sad,

I have to tell that I sent my iMac to Engineers, but they didn't repair my iMac (Core Duo 17")

 

What I did:

• I have created a new Boot Driver inside the EFI Shell

• I chose a Windows Vista "EFI-Bootfile" and then set "Next Boot Driver" to "WindowsBoot" (This is what I

called the newly created Boot Driver)

• Then I rebooted the iMac

• The screen is black, no reset (by pressing the Power button) possible

 

So...is there a way to reset the EFI?

I mean, there has to be some way to set the "Boot Driver" (which I changed) back to the default.

 

Please I need help!

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SteveM
SteveM
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Not 100% sure it'll help, but it has for me before.

 

Insert Mac OS X install disc 1 and hold down C during startup until the select a language screen comes up. From here, Go under the utilities menu and select startup disk. Select your mac os x volume and click restart.

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SteveM
SteveM
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OK, but the problem is, the Firmware doesn't start up,

means there must be a reset button somewhere on the logic board, that resets the Firmware...Without the Firmware, it doesn't even start from the System DVD

 

 

 

You can't get back into the EFI shell?

 

You were using the Intel Sample EFI menu, right?

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SteveM
SteveM
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• The screen is black, no reset (by pressing the Power button) possible

 

Ok judging by that statement I'm guessing you've already tried this? But if not, try it.

 

1. Unplug all cables from the computer, including the power cord.

2. Wait 10 seconds.

3. Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer (this resets the System Management Controller (SMC), similar to resetting the System Management Unit (SMU) on a G5 class machine).

4. Let go of the power button.

5. Reconnect the mouse and keyboard.

6. Press the power button to start up your iMac, and reset the NVRAM by holding command-option-P-R at boot time, waiting until a second startup chime is heard.

7. If the iMac still does not boot from its hard disk, you may need to boot from the DVD installation media, reformat the drive, and restore the operating system.

 

from appleintelfaq.com

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DeathChill
DeathChill
Posted
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By following these steps, the iMacs that had difficulty with certain EFI modules appear to have been restored to a functioning state:

 

1. Disconnect the internal hard disk

2. Disconnect the iMac from AC power

3. Plug in AC while holding the power button

4. Power up the iMac and zap NVRAM (cmd-opt-P-R)

 

The hard disk can be reformatted and the operating system restored.

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WandaLust
WandaLust
Posted
Posted

cmaus

 

I had similar issue - Black Screen unable to get NVRam to reset etc etc.

 

I tried the remove powercord like stated in other posts however just turned my mac into a funky hairdryer.

 

After several attempts I decided to go for broke and strip down the mac and disconnect the hard drive.

 

I removed the memory from the slots, disconnected all power and discoennected the hard drive.

 

Then while all was disconnected I plugged in the power cord and keyboard/mouse. Booted up the mac whilst holding down the apple/alt p & r keys all at the same time. Waited for the mac to boot up and then held on for the second chime.

 

It finally booted and I reconnected everything then booted back by holding down the alt key and switching to ensure that I booted from main hard drive (this reset everything and I didn;t need to rebuild mac...phew).

 

In short to summarise.

 

1) Disconnect everthing (Power/mouse keyboard).

2) Remove memory.

3) Disasemble mac and disconnect the hard drive.

4) Reconnect power lead and keyboard/mouse then reboot whilst holding down the apple/alt/p/r keys. Wait until mac beeps twice. (NVRam has been reset along with EFI settings).

5) Shut down and re-assemble mac. (including memory).

6) Reboot and all should be well.

 

If this doesn 't work then your imac is fried...

 

Good luck

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WandaLust
WandaLust
Posted
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cmaus,

 

Just a follow up as I managed to trash mine again while playing with the EFI.

 

Have you tried disconnecting the hard drive then rebooting with the HD disconnected ?

 

Reboot and hold the NVRAM reset keys (p.s you need the memory in or it won't work, ignore what I said last time).

 

I have managed twice now to screw the EFI and restore so if this really doesn't work then it is totally shot.

 

Make sure you boot with HD disconnected (I do this by disconnecting the black lead which runs from the hd to the board). Powering up with kbd and mouse connected whilst holding the alt apple p r keys.

 

What happens when you try that ?

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cmaus@mac.com
cmaus@mac.com
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Isn't there a secret button inside the iMac which resets the EFI?

I mean, does anyone know where in the iMac the EFI is placed? (Any chip containing the EFI?)

Someone told me the EFI has to be "reflashed". But I don't know what this means, and if someone knows, how can I do anything to my EFI, or the chip containing the EFI?

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cmaus@mac.com
cmaus@mac.com
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Well, sure...

I used the Intel-Developer Preview of their EFI-Shell as you know...

And I downloaded the early "Windows-on-Macbook" pack from this site: http://neosmart.net/blog/dual-booting-wind...p-on-a-macbook/

 

(I hope you know what I mean)

Then I created a new Boot Driver in the EFI Shell, and selected one of the EFI-files from the "Windows-on-Macbook". (None of those EFI-Files did really work)

I named the new Boot Driver "WindowsXP-Boot"

 

Then, I chose "Next Boot Driver" and set it to "WindowsXP-Boot"

--Restart--

 

Black screen...forever(?)

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WandaLust
WandaLust
Posted
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As I understand it there is no reset button on the board for the EFI.

 

The EFI is stored on the Boot Rom (like old style bios) and unless you have flashed the chip the reset sequences should work. (Emphasis on the should because as we know nothing in life ever follows that pattern).

 

The steps that have been described by myself I can re-iterate do work. My experience in loading drivers which cause the black screen (done it three times now) and have recovered everytime. Could try disconnecting the battery also but I don't think that will help.

 

If the BootRom has been corrupted (not sure what the NeoSmart stuff did as the link is down) then you need to get a firmware update and reflash the BootRom. The problem here is that I don't know anywhere where this is available as you would need the original from apple.

 

Sorry we don't seem to be helping you much but all we can do is tell you how we have recovered and I am sure there are loads of us out there which have gotten to this point.

 

Can you answer the following questions ?

 

1) Is the EFI shell booting from the OSX partition or an external drive.

2) When you do the reset (with HD disconnected) does the caps lock button flash on then off at any point when holding down the ALT APPLE P & R keys (All at the same time) ?

3) Does the Apple Respond in any way to the PRAM reset (alt/apple PR keys) ? i.e does it reboot or just do nothing.

 

I would also suggest placing the OSX DVD in the apple doing the pram reset and then trying to boot from DVD.

 

If there is no life at all from the keyboard then it looks like the Boot Rom has been corrupted and then you have a dead mac. I don't know if there is any recovery from this without sending it off to apple or dropping it on the floor and claiming it on your insurance...

 

I am hoping that somewhere one of the instructions has been slightly missed and we can get you back on line, but if not I think U may be doomed to taking it in for repair.

 

So if you could just detail the steps you have followed to reboot just so we can isolate if there is anything obvious that could be tried.

 

Failing that then the firmware has been damaged and needs to be restored by an engineer.

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cmaus@mac.com
cmaus@mac.com
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Yes, I disconnected the HD (it lies somewhere around)

Then I tried to press and hold the power button while I plug the power lead back in

as described above:

 

"1) Disconnect everthing (Power/mouse keyboard).

2) Remove memory.

3) Disasemble mac and disconnect the hard drive.

4) Reconnect power lead and keyboard/mouse then reboot whilst holding down the apple/alt/p/r keys. Wait until mac beeps twice. (NVRam has been reset along with EFI settings).

5) Shut down and re-assemble mac. (including memory).

6) Reboot and all should be well."

 

But it didn't work at all...what happened to my EFI wha didn't happen to all the other guys who broke it?

 

And: Speaking of the PRAM Reset...

"...you'll hear a second chime"

 

There isn't even a first chime.

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WandaLust
WandaLust
Posted
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CMAUS,

 

Please can you try to do the reset without your first step.

 

i.e don't hold power key whilst plugging in the power.

 

"1) Disconnect everthing (Power/mouse keyboard).

2) Disasemble mac and disconnect the hard drive.

3) Reconnect power lead (Don't hold the power key at this point) and keyboard/mouse then reboot whilst holding down the apple/alt/p/r keys. Wait until mac beeps twice. (NVRam has been reset along with EFI settings).

4) Shut down and re-assemble mac.

5) Reboot and all should be well."

 

Fingers crossed that it's just the power cord/power button option that's an issue

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cmaus@mac.com
cmaus@mac.com
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The fact is still, that the iMac doesn't respond when I press any keys on my keyboard...but it turns all the vans on, when I do the procedure with holding the Power button while plugging the power lead back in (just wanted to point out that there is a difference)

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WandaLust
WandaLust
Posted
Posted

CMaus,

 

Mine did exactly the same, Plugging in the power lead whilst holding the button did nothing for me whatsoever, except what you describe all the fans blast on and still get a black screen. Whoope ....

 

So all I can say is what I have said before to reboot with the Hard Drive disconnected and the PRAM reset. This worked for me and has multiple times.

 

I know the following is obvious but I can't help any more than what I know works for me:

 

 

Are you 100% sure you are running with the HD disconnected ?

Is the Keyboard Connected ?

Have you removed CD from drive ? (if no does holding the right mouse button down on boot up work ?)

are you holding all the keys simultaneously ?

are you holding the right keys ?

are you holding the keys long enough ?

 

I know it all sounds stupid and basic but if none of these work then you must have hosed the firmware. Don't know of any reset buttons or firmware uploads you can get to repair this. You will have to either take the imac for repair or throw it in the bin....

 

 

Sorry but I am doing the best I can here :graduated:

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