Chosen Solution
My FZ18 wont turn on and batteries ( I have 4) are all good. Initially when I put a freshly charged battery in I could take a photo and then the camera would shut down and not start up again so don’t know if it’s immediately discharging battery but now just dead
Is there any error message displayed on the camera LCD? When you take a photo, does it say “please turn the camera on and then off again” Or does it immediately shut off? Try inserting the battery into the camera and hold it in while turning it on. See if it stays on. Maybe the battery housing got slightly damaged from a fall and the battery is not seating in properly. Good luck!
Have you tried with an external power supply? 8.4V power supplies are widely available and cheap. You will probably need an adapter to fit the socket on the camera. Search on ebay (for example) for something like “8.4V 1A Mains AC-DC regulated Power supply” and then for “8 in 1 AC DC Power charger adapter tips”. But maybe check the switch first: the switch on the case can come disengaged from the “real” switch on the circuit board. That would explain the problem. But that involves opening the case. The service manual is available online, but doesn’t exactly match my FZ18. I would post a link to a blog where I describe how to open the case, but ifixit seems to dislike such links.