ASUS memopad 10 ME102A won't charge unless it's off

Hi!

i'm new to this forum and must apologize for my bad english in advance.

My friends Asus memopad had a broken USB connector and he asked me to replace it, so i did, using a SMD hot air gun and soldering paste.

everything went smooth and nothing was damaged on the motherboard after the repair...but here is my problem :

The tablet will only charge when it is off.

it does not recognize the charger when it is put on, nor will it connect to the computer.

I guess that there is a chance that the old broken usb port had some pins inside that was short circuited and destroyed some IC.

but does anyone here have any suggestion on where to start looking? I have tested with several chargers and cables..