iTunes Error 14, iPhone 5

Hi all

Yesterday my phone suddenly powered off when using it. I tried to power it on again, but the Apple logo was in a loop. So I tried to restore it with iTunes in DFU mode.

When restoring I get everytime error 14.

What I already did:
Using a new USB cable
Replaced the battery
Disconnected the LCD
Removed the .ipsw files

Could someone help me to solve this problem?