1. Open the case
2. Disconnect the battery for 24 hours
3. Observe the electronic board, eventual traces of defective components
4. Connect the electronic board to the USB port (battery still disconnected)
Do you hear a slight beep ?
YES, proceed to step 5
No, proceed to replace the controller card
5. USB still connected, connect the battery
If the battery is charging: problem solved!
If not: change the controller card