Phone is dead after proximity replacement

Hello, today I replaced the proximity sensor cable on my iPhone 4 because the power button doesnt work.

Now the phone is dead. I'm really sure that all cables and screws are on the right place.

I can't start the phone. I connected it with my PC and iTunes recognized it automatically in the dfu mode. I tried to recover it but it doesnt work. The phone stucks at the process "prepare for recovery". I tried it again and let the PC 2 hours running but nothing. After 3 minutes, it stucks for the hole time on this process.

Is this error known?