iPhone 6 plus not turning on normally and not charging

Hello,

I am facing a few problems with my Iphone 6 plus. It all started with the charger from my sister. My own usb cable didnt work anymore so i used the spare cable of my sister. But since yesterday it says that the cable is not supported when charging and the charging of the phone stopped. I bought a new original apple charger and usb cable but now the phone doesnt charge at all. When i insert the charger in the phone and turn off the phone, the battery will charge itself but very slowly. After an hour of charging, i would turn on the phone and the battery % would only be 10% more. And as soon as i turn on the phone, charging stops.

I went to a repairshop and they changed the battery and dock connector, but all without success.

Beside these problem, i have another one. When i turn off the phone and want to turn it on it does not boot up from the first try. i have to perform multiple hard resets before the phone turns on again. I thought it may be a software issue so i restored the phone through the settings . But during the restore process as soon as the first white bar is full and the phone wants to reboot to complete the restore, it does not boot. I left it for 10 minutes but nothing. I had to try the hard reset button combination several times before the phone would turn on and complete the restore process.

But the next problem is here: when the restore is complete and i want to activate the phone and want to set up touch id, i cant complete the set up because the configuration text for the touch id is all cropped and messed up, i cant press next to go to the second part of the scanning to complete the fingerprint setup. It worked great before the restore though. Is this because the phone couldnt boot itself up during the restore process and so something went bad with the software? U can find a picture of the problem during the fingerprint set up here: https://ibb.co/iXFPS5

Also the camera is not working after the restore. The lens stays closed and the camera app is unresponsive. When switching from filming mode to photo mode the camera suddenly works fine sometimes.

My questions are, why is my phone not charging? And why does my phone never boots up the first time i try to boot it up? Is it linked to the charging? And what explains the touch id set up problem and camera problem? Is it really just because of the bootproblem? I want to install a fresh copy of ios 10.3.2 through itunes, but yeah... not recognized. I appreciate any help.