Battery powered lights “faulty” (Crystal Palace SE19)

These are 10 or more boxes of different types of battery powered fairy lights - they were returns that came in a job lot - some sets of 200 some 100 etc . I was going to fix them ( haven’t tested them even ) I think they could easily be fixed or maybe they work anyway . Someone has the time and skills for this ? ! Fun project .

Fair Chance Policy: I’ll wait before choosing a recipient to give more people a chance to reply.