I have been able to fix battery problems by taking the unit apart and cleaning and bending these contacts up and putting dielectric grease on them. I've done this twice in 4 years and it has worked like a charm each time. If you use external power I would recommend disconnecting the tiny internal connector. Then try to clean the contacts on both sides and put dielectric grease on them too. And while you're at it clean the grease the contacts on both ends of the external power connector.