Fixed my my Bose Quiet Comfort 15 that would not power up! Fortunate because the battery wire broke at the solder point on the battery door. Did not need to disassemble anything, just wiggled the door loose. Removed 1" insulation from a piece of junk wire, twisted the strands. Soldered, not to the door, but to the base of the spring. Then re-installed door, trimmed wire to about 5/8", crimped it to the end of broken one and soldered that. No need for any insulation, here. Difficult to get door closed but WORKS - at least until the next battery. I SHOULD have put a little heat shrink, not for insulation, but for strength. FYI: although my unit is many years old. my local (USA) Bose store will replace with refurb for $120.