iPod Touch 4th Generation Screen Won't Turn On After Home Flex Replace

After replacing the home button flex cable, I tried to turn the ipod on and nothing happened. I plugged it into the computer and it recognized it, but it has a passcode, so I can't restore it. I don't know if the new home button works or not, but I can't turn it off to put it into DFU or recovery mode. The flex cable for the screen doesn't look damaged. I can't see anything at all, so I don't think it is the back light. Is there any way I can fix this? Do I need a new screen?