HTC ONE M7 - randomly reboots also charging, but neither pc nor phone doesn´t detect any connection.

[Filip Kovarik]

Hello guys,
I bought used HTC ONE M7 around two months ago (it doesn´t have warranty). When I first plugged the phone through original usb cabel to a PC it started charging, but neither pc nor phone detected any connection (I made myself sure that problem is neither in cabel nor in pc usb port.) I also noticed that when i was using an application (for example built in gallery) mobile sometimes randomly rebooted itself (at first reboots were rare, but as time went by, the amount of reboots per day were increasing).
I searched on the internet and found few "solutions" but neither of them helped.
1)I have tried factory reset.
2) Booting into safe mode to find out if 3rd party app isn´t causing the problem.
3) I replaced usb flex in the phone.
4) Also i read somewhere that reinstalling system might help, but I am unable to do so because of no usb connection to pc.

Here are some of my specs:
Andriod version: 5.0.2 (newest available at the moment)
HTC sence: 6.0

I can provide more information if needed.

Thanks for help.