Non-jailbroken iPhone 4 GSM completely unresponsive

Hey guys! Yesterday, a friend of mine approached me with his iPhone 4 GSM and asked if I could update his phone to iOS 7 since I have an Apple Developer's License (yes, mine is legit- I payed $100+tax through Apple). I agreed, registered his device's UDID, downloaded the correct version of 7, and off we went! However, after the update, the phone was stuck in a very odd bootcycle... the Apple logo would appear and stay stagnant for about 10 minutes, then it would go away for about 1 minute, and repeat. Usually bootcycles are far quicker, so I figured the update must have been corrupted somehow (though everything went perfectly like the other devices I had updated). I went ahead and unplugged it, plugged it back in, backed it up and option+restore using the iOS 7 .ispw just incase he had jailbroken it before, but forgot he had. After the install, it went back into the same weird bootcycle. WTF!?! I approached him and said that something was wrong with the iOS 7 download, and that I was going to restore it back to 6.1.3, the same firmware he had on it before the whole deal. I got a couple of "device not eligible for requested build"'s and "error 1601"'s, so I hooked it up to the newest Redsn0w and threw it into PwndDFU to see if that would make it take the firmware. Well, not the phone is completely unresponsive. iTunes, RedSn0w, TinyUmbrella, iFaith, iREB: nothing will recognize this blasted phone! The screen is black and it will not boot up, or even show the battery status. Neither hard rebooting nor DFU mode does anything. Any help would be greatly appreciated!