Dso nano V2 wont upgrade firmware or connect to PC

Went to upgrade to new firmware. I found that I could not connect to USB host. (PC says USB device has malfunctioned) When I connect via USB cable screen dims on the nano as if charge is being drained through nano back to PC. This started when I left the nano charging overnight. The next day the battery was toast so I replaced It. The nano works fine except this one flaw.
I think it is the charging circuit (linear technology LTC chip) but I am not sure. I suspect this because it will overcharge the battery (I haqve to watch it) and if I turn on the scope while charging I can see 3V oscillations on the screen.
Any help or comments appreciated. I would like to fix it myself.
Thanks guys

I forgot to mention when I plug into USB and attempt to turn it on the screen stays white. If I power up then turn on and plug in USB screen dims.
I bought mine from Nkc electronics. I would send it back if I knew it would be repaired at no charge. The only mod made to it Is I glued a small compartment on the back to install a larger battery and a integrated stand. The symptoms were present before I did this mod. (battery dead, no charge or turn on)