I just got two md-ms702s on ebay. listed as 'mint condition' but neither seems to be charging the battery. on one, the battery symbol shows up when you press 'stop' twice, but then disappears. i need to do some recording next week, and was planning on using these. i can also borrow a jb3 from a friend, but would rather use my own equipment. Does anyone know how to rig an external battery pack with supplies from radio shack? Also, does my problem sound like the units are defective, or would totally dead batteries be unchargable and do this? thanks!