When I insert a fully charged battery into the P2v it does not start up. Pressing the 'on' switch shows 4 green bars but wnen holding the 'on' switch to start up the P2v . the switch flashes red after a few seconds. I have three batteries and all act the same way. They have not been used for several months but were stored at approx 50% charge. Any suggestions? Battery problems or P2V internals?