When i changed my car
battery, i connected my
battery charger to the
battery leads and switched on. Then disconnected the
battery leads and changed the
battery. Much lighter wiring, crocadile clips for simple connection, no loss of data, and cheap solution. Sorry not much help to you but might be an idea for next time. Also for around £20 you can buy off ebay, a maintainance charger if a normal wet cell
battery, and have access to mains electric when in storage. Uses very little power and keeps your
battery fully charged.
Hope you get fixed ok.