Modern Vespa

Ok so I just bought a new battery for the scooter, after it sat for a few years. Started up after some "massaging".... now about a week later, after the scooter sits for about 24 hours, when I press the electric starter, the entire electrical system is killed, the lights go off, the check oil light goes off. The only way to try to start it again is to touch the battery with a screwdriver, then put the key back in and then the electric starter turns the engine over, and then it will start. Any ideas?

My thought is that it is not grounded properly, perhaps running an additional ground wire from the negative terminal to the engine block?

Thanks in Advance for help

???

As everything dies, it could be just one of the battery connections that is faulty going by the above - but do check the condition of the main fuse and its connections, as in accessing the battery you may be giving that a nudge.