Mobi V17 Pressure Washer – Charge Problems

I have had four Mobi Units now and they have all suffered from the same problem which comes on after a few months use

(giving up with them entirely due to leaky seals is their eventual fate!)

They fail to charge.

Plug the Mobi Charger in and the Charger shows Green even though the battery is flat.

I’m not sure if the charger is at fault ? There doesn’t seem to be any replacement Chargers online to try. Or is the Mobi Unit at fault ?