Charging/USB doesn't work except when turned off, phone reacts to USB-cable but crashes seconds after charging begins

[AnotherElk]

It’s perhaps time for an option independent from the phone as a makeshift measure …

@AnotherElk

You could also try to charge the battery not in the phone, but with an external charger.
I got me this one , pretty cheap and does the job if needed.
It’s a generic China piece being sold under different brand names all over the internet.