Not Booting displays apple logo then blue or red screen

Apple iPad Air 2 (A1475) WiFi/Cellular

Hi ,

I recently changed a digitizer on an Apple iPad Air 2 and everything worked fine.

Customer had mentioned that it was taking a long while to charge up but it seemed ok when benched.

However the customer used it for about a day, recharged it and it died, saying it " sort of faded out" then got a flashing blue screen.

He returned it, we tried to charge, couldnt so changed battery. It nows starts to charge, stays at the apple logo and either red or blue screens.

Tried recovery - didn't work as it cuts out when it tries to update (I presume)

Any Ideas???

Martin