9. Back wheels spin very slow but it never actually takes off. You can hear the engine run, but it just doesn’t want to go (even though the battery has been charged for 18 hours).

Do a Battery Test

If battery is no good, you need to replace a battery. Click here for detail.

If the battery is good, you may check the gearbox to see if “slipping” or stripped”.

Do a gearbox test

If the gearbox is no good, you need to replace the gear box. Click here for detail.

If the gearbox is good, you need to replace the controller box and main wire. Click here for detail.