In case you need the plugs, check out Molex Pico EZmate plugs. RS-online order numbers (molex part number) 700-0820 (78171-0002), 7001013 (78172-0002), 7000830 (78172-0410)
To unplug the plug, don’t pull to the side, but lift it up towards you. Instead of trying to crimp the cable.
Hint: You most likely won’t have the crimping tool for those plugs. They are really small. Instead unplug. Cut the cable in the middle and solder your new battery to that.