when it comes to mobile phones repair, you must be able to take voltage readings with either opening the phone and using probes or using a usb ampmeter to verify voltages being input to the phone. without these tools, you will never know if it truly is not taking any volatage for charging or anything else.
do you have these tools? are you able to buy them/borrow them? if yes, please let me know what voltage and amps it is drawing.
If not, unfortunately you will need a technician, or replacement.