Hi all ,just bought a spare bosch 400 battery for my haibike 2016 off ebay ,its brand new never opened ,charged or used by the guy ,took it out the box ,pressed the side button and NO led lights show ,connected it to charger and its not charging at all ..is there a sleep mode these batteries go into if not used if so how do i get it out of it, or has it just been stored for too long at half power and now the volts have dropped so low its unreversable ie knackered ,i think its been stored unused for approx six months cheers mark