I've only had this bike since Thursday and whilst being impressed with it, I had an issue the first time I reconnected the battery to the bike - the bike wouldn't switch on. I tried again several times and eventually it did work. After that things seemed to be OK, until this morning when I reconnected the battery again and it wouldn't work. Pressing the button on the battery showed no lights so my first thought was that the battery was depleted, despite it showing full charge when I took it off last night. I connected the battery to the charger again and the lights came back on, this time showing full charge. I connected the battery again and it worked perfectly. Any ideas what could be wrong?