You don;t say how old the bike is or whether you have just bought it - which may be important if it is new
The symptoms you describe COULD be due to the battery having very little charge left in it - which normally happens when you have done some miles (obviously)
If the bike is new then you don;t know how long the battery has been sitting around in a warehouse - they don;t like being left alone and I have seen some that arrive with a battery that is pretty dead. In fact the first Carrera we tried to buy from
Halfords had a dead battery and we had to wait for them to get another one in!
SO - if it is new - take it back and do not play with it - they have to fix it for you but if they can see you have been having a go yourself first then they could claim they no longer have to fix it for free - if they want to be awkward - which may not be likely but ......
if it is a few years old they the advise above is a good place to start - also try the bike with another battery if this is possible??? and try charging the battery from another charger - again if possible