Hi, we bought a 2011 Kalkhoff Agattu recently which was honestly advertised with a faulty battery. However, on getting it home it has some charge (2 lights) and powers the bike but it won't take any charge. If you press and hold the button it shows 5 lights so we're hopeful it might not be completely knackered. It is showing 25.3 volts (8ah battery) but that doesn't increase after charging, nor do the lights show when you put it on the charger (we've tried 2 different chargers that are working fine with other batteries). Has anyone come across this before or have any idea why it won't charge?