I had a very stable T420S running Maverick 10.9.5 (using your excellent guide) -- no issues with sleep. After upgrading to Yosemite using your latest uploaded files, I cannot boot from the hard drive. When I boot from hard drive, the screen fades to black after the Apple icon shows up (the computer is not sleeping since I hear the fan running).. I can boot using the external Clover USB (your optional method at the bottom of guide). However, when I boot using the external USB, thinkpad does not sleep when the lid is closed. Any suggestions?