Hi, i had the same problem twice...!!!
My battery was ok, everything was ok but
the beep keep going on, for overload...
Both times i fixed doing these steps...
- Turn off the unit
- Flip over the unit
- Open the battery-cap and turn the power on
- Green Light is flashing
- Try Now (with the green light flashing) to disconnect the battery...
- Now it should be ON with the Empty battery light on (Red light)
- Connect again the battery as it is...
Now it should be ok...!!!
Good Luck...