First, that service amount is spot on for Ducati...and it's not just an oil change. Review your Owners Manual. Second, it doesn't sound like the mechanic did anything wrong. It sounds like a bad battery and bad timing. The battery is sealed and should not leak. All the mechanic did was check to make sure it's still tightened properly. I doubt you will see any reimbursement.
Good luck and let us know the outcome.
Good luck and let us know the outcome.