Hello. I'm having a minor problem (hopefully) with my iPhone 3GS. Please read the whole story if you can. The "Jailbroken" Part When I bought it from an eBay seller, it was jailbroken, but Cydia was the only app visible (which was the reason for it being on eBay). So I fixed it by restoring it to original factory settings, I then jailbroke it myself, and it was working perfectly fine. Then, whenever I let it idle WITHOUT it plugged in, and when came back to it, I pushed the home button, and it wouldn't turn back on. After that, I force-restarted it (Home + Sleep button for 10 seconds), the Apple logo shows up for about 5 seconds, then a white screen appears. I reboot it the same way again, but the second time, it stays in DFU mode (nothing but the screen being completely off). Whenever I plug it in and try to restore it, it says: - Your iPhone "iPhone" could not be restored. Error code (21) Luckily, since I'm good at taking apart/repairing Mac hardware, I disassembled the iPhone and unplugged the board from the battery for a few minutes, reassembled it, and it worked just fine again. The "Un-jailbreaking" Right after I got it to work again, I decided to un-jailbreak my iPhone by restoring it normally, and with success. It's 95% original now; However, sometimes when I let it idle like I did when it was jailbroken, the same thing happens, but now, this happen much less frequently when I let it idle, and on top of that, I reboot it, the iPhone boots normally like nothing happened. Let me give a few extra facts about the iPhone when this happens: The iPhone does not do this while playing music The iPhone was always charged at least 60% It NEVER does this when plugged up to anything regardless of it being jailbroken Error code 21 shows up in DFU restore mode regadless of jailbreaking, but it has the capablility of restoring normally I can no longer jailbreak the iPhone due to the presence error code 21. Any help would be appreciated. Thanks, and I apologize for the long story.