Atrix will boot up but unlock screen is unresponsive
i had the same issue with screen not coming to live after proximity sensor has turned it off once. I tried to boot in safe-mode and the phone is working perfectly  and there is no such issue in safemode. I know this is not permanent solution (there must be some limitations of safemode, though i have no idea about them), but it atleast points us that this is not hardware problem and some application is messing up with the proximity sensor.