I was trying to troubleshoot audio streaming issues between my SSL Nucleus Soundcard/Control-Surface and my new iMAC running 10.10.5.
As it turns out the Nucleus is USB2 and all my iMAC ports are USB3, and SSL do say that there are issues with this configuration, and indeed the audio performance is really bad. After some googling i thought i found a way to turn my USB3 ports to USB2 'mode' by adding a kext file via kext wizard to the IOUSBFamily.kext extension.
I made sure I backed up the original IOUSBFamily.kext, rebooted and here i am with a dead iMAC: none of my bluetooth devices (Magic Mouse, Magic Trackpad, Apple Wireless Keyboard) are recognised and I can't login, it just sits there at the login screen but i can't point my mouse or type my password. I tried to take the batteries out of all peripherals (put them back into discovery mode) and reboot the iMAC but nothing. It even does not seem to complain that there is no keyboard/mouse attached. I tried plugging in a USB mouse but it also doesn't register. I don't have a USB keyboard in the house to see if that would register.
I can see the iMAC over the network but have only turned on File Sharing unfortunately. Using my MacBook Pro I can browse to the /System/Library/Extensions directory on my iMAC, but cannot delete the corrupt IOUSBFamily.kext file and replace it with the backup one due to permission issues. I've tried SSH-ing to the iMAC but SSH is turned off.
I tried resetting the SMC but that didnt help. I can't get into any of the special Startup modes as i cannot get a keyboard to attach!
I am trying to borrow an USB keyboard or burn Yosemite onto an USB drive, but I fear its no use as none of the USB ports are recognised.
It does seem the Thunderbolt ports are working as i can connect my MacBook Pro to the iMAC using a Thunderbolt cable. Unfortunately i don't have a Thunderbolt to USB dongle!
Any idea how to approach this ? Thanks!