ok so i have my sgs2 for a little over a month now and everything has been awesome until last night , i was using my phone just texting and then i set my phone down for maybe 10-15 minutes then when i hit the unlock button to use it again the screen would not light up....even holding the button would not turn on/ show the off power menu, nothing would happen....the only way to get the phone back on is to do a battery pull,,,,so i thought it was just a weird bug and let it go ...well probably 40 minutes later it did it again....the phone works fine when the display is on but it seems like when i set it down for a certain amount of time the phone turns off and wont turn on even with the power button, only after pulling out battery then the button will work,..its happened 3 times since 11 oclock last night?? has anyone else heard about this problem before? and yes the phone was fully charged but after having to do a battery pull and turning the phone back on the percentage dropped about 40 percent
This does sound like the sleep of death syndrom...but he says that it's completely stock. Usually this only happens if you under clock or under Volt the cpu.
My advice would be to put your phone into recovery mode and reset it to factory settings. You will lose all of your data though so do a backup first...oh, wait your not rooted...Not sure what I would do then.
I had a similar problem with my Infuse. However, my Infuse never did turn back on and had to be swapped out.
I think the best thing to do is to hard reset it. If that does not fix it, then take it back to where you got it. Even without an insurance policy it should be under a manufacturer warranty.