So Yes, I had the same problem and have resolved it. Just to be clear for those about the open the case, if the unit powers on when connected to power or usb, but not while free-standing, then it is likely that it is the battery wire. You can open the case as it is snapped together, but this must be done carefully to minimize damaging the case. A good idea is to have a set of very small flatheads, or precision screwdrivers. Start by inserting the thinnest screwdriver head into the base of the unit, and rock it back and forth so that you can slide the next size up driver in the gap. Continue to do this, and leave one driver in the base as you work the other around the corners. You may want to review where the “clips” are that hold the unit together, right near headphone and data ports (so don’t jam in screwdriver here).
When you have it apart, it is likely that the red wire is disconnected, and you can simply use the existing solder by heating it up. Make sure the solder iron has a very fine tip so that you hit only the space on the board where you need to connect the wire. The trickiest part for me was stripping the red wire, a cheap little one-size-does-all wire stipper did the trick. The right tools again and a steady hand saved a lot of frustration.
I did not remove the board from the unit before soldering, but many suggest it. Hope this helps.
