Hi. I have a Precision 7720 and it refuses to turn on when I shutdown or put it to sleep for some hours. When I try to turn it on, the power led and keyboard backlight turns on but goes off after about 2-5 seconds. I have tried hard reset, checked the hard drive, ram and cmos battery but it still won’t come on. But when I leave it for some hours and come to turn it on, it does. I’ve run diagnostics and no problems have been found and it works just fine. This has been going on for days now and I haven’t been able to find a solution. I’ll really appreciate any ideas on how to solve this problem.