Wont come past Apple Logo after DFU Problem

Hi guys,

I replaced the Screen of my Iphone 5s, after that it powered up into the activation screen(it was restored). I then sent it to a buyer called rebuy.com who then sent it back telling me its broken. So i dont know what they did but it was stuck in DFU-Mode since then. Restoring via itunes allways interupted with the Error Message -1 and notifying me that the phone has been disconnected. So i then installed RecBoot and pressed Get out of DFU-Mode, after about 2minutes of loading it said, that the process failed.

The Status of the Phone now:

Itunes doesnt recognize it.

Neither does the PC.

Its turned off, when i hold the ON button the Apple logo appears for about 5-10 Seconds, then it turns off again.

Cant Put it into DFU-Mode

Thanks in advance!