I am having this same issue now. The battery used to make a satisfying "click" when I installed it, now it does not. No power to the guitar. I have lots of guitars and I have to say I like this JTV-69S much more than I thought I would. That said, if it's not reliable, how can I gig with it? Any suggestions to get the battery to connect again? And yes, it's fully charged, lol. :-)