I just fixed mine. these Gtech cleaners have a BMS built on the top of the battery cells which are a bit temperamental to say the least. mine suddenly switched off with the front lights flashing and wont charge. so in order to reset the BMS you need to disconnect one off the negative or positive battery terminals. i did this and added a switch on top of the battery lid so if it ever happens again i just flick the switch to reset. simple fix :-)