Boot loop after digitizer replacement

Hi out there,

I really need some help here!

I just helped a co-worker replace the digitizer on his iPad 3. This is nowhere near the first time that I have replaced a digitizer on an iPad, but definitely the first time that I have had this issue.

I of course tested the device after the replacement and everything seemed to be working fine and they were able to use the ipad for some time befor it started acting up.

The iPad seems completely dead. Nothing happens when it is plugged into a charger nor a PC. After about 3 minutes, the battery charging symbol appears and a few seconds later the Apple logo appears. Just before the device boots, it shuts down again and I have to wait another 3 minutes for the Apple logo to appear agian.

I have tried to do a hard reset, but that has no effect what so ever and I have tried to refit the old digitizer - with the same issue.

The iPad is not recognized by a computer until it has almost booted and that is only for a few seconds until the iPad shuts down.

I would be HUGELY greatful if someone could help me out here or point me in the right direction.