Nitecore HC60 charging problem

I’ve had a Nitecore HC60 for 2 or 3 years and the charging circuit has never worked. I didn’t make a big deal about it when I received it, but now I’m interested in fixing it if possible. When the micro usb cable is inserted, the charging light comes on as if it were charging, except it actually discharges the battery. The light works fine otherwise, that’s why I just accepted it.

I’ve taken it apart and cannot see any obvious problems. No obvious bad solder joints etc. Of course I’ve tried different cables and compared results with a friend’s good-working HC 60.

Anyone ever have a similar problem or have any suggestions?