Hello, you can also connect whole cable of charger to battery, but , attention.. ! You must connect right polarity , + pole of charger to + pole of battery and - to -... After that , you must charning the battery like that about min 30 -45 min.. I think, that will be better, if you know someone who have mulitmeter for measuring voltage, cor correct finding where is + and - at the power charger cable. After 45 min you have charged battery and you can upgrade your firmare