@crxr..
i'm not an iphone user.. but as a technician.. you have full responsible to the item that given to you by its owner...
when you damage the item then its ur responsible to replace it.I did damage a customer pc motherboard, but then i replace it
with a new board.
In this case, its seems that you dont want to responsible on what you do....
and yes.. he is being rude to you... but if it was me.. i already punch your face.. you know y?..
1. The item is so expensive, the price is like buying a notebook.
2. You given hope to people so that he trust you that you can do it easily. You said like you are pro.. yet.. u damage the phone.
3. When you buy an expensive item, you will love it.. its so painful when other broke it..especially the one who u give trust to repair it
From the owner words, its seems only the earpiece is not working, then why its screen suddenly malfunction?...
then you blame his board?.... as same from the previous comment's, have you test that the touch screen is working or not
before you disassemble it?.. its your responsible to check it before you disassemble it..
so crxr..
this time your customer win. i cant be on your side, because you are the fault one. i hope the person who support you is not
your friends. please dont deny it... you just make thing worst, i got meet technician like you, it look like he can do anything, but in the end, so frustrated

I agree with you... I also doing something like you if the item damage while in my hand. (I also doing some hp repair too)
And I also in TS situation before (happen in 2 weeks ago). I just want to change my expensive Guess watch battery which only cost RM10 but end up there is some damage to the outer body and back cover because the so call pro watch technician cannot close the back case perfectly. I just ask how solve that problem. So the lady explain what can be done and the cost will not be bear by me. After 2 call made by the shop, I getting back my watch good as new. Just pay the battery.
Good luck to both party to solve this issue fair and square...