iPhone dead after drop. (Motherboard related!)

Dear ifixers,

A costumer came by with an iphone 6 that was dropped, the phone had no visual damage's. After the drop the lady said to had a bleu screen on her phone and after that the phone was dead, doesn't charge or anything.

I got the phone, and after replacing some parts i still booked no succes so i tried placing the motherboard in a well working iphone 6 to see if the problem was caused by the motherboard itself. Phone still didn't do anything.

I connected it into itunes and there was a "small" connections for just a second afterwards even that didn't worked anymore... It looks like its dead, tried resseting, disconnecting the battery and gave it another try, still doesn't do anything.

The only thing the phone does is when its plugged in, it makes a clicking ("electrical") noise, not really loud (only audible when the phone is opened)

What could cause this problem, where is it located ?

And off course is there a fix for it ? :)

Is there anyone that could help me out on this please.

Thank you for your time to read this, hope you could help me out :s

kind regards

Koen