my bose system is the soundlink wireless mobile speaker. It was unused for a few years, but later plugged in to only find out the battery maybe dead as the system didnt turn on and kept flashing red light. have tried it all but it doesnt work. The mute button brings it back to yellow Soild but soon starts flashing with red light. There are no firmware upgrades for my model. Now i have sourced a new battery but it still does the same. Left on overnight charge but in vain. Any solutions? Help needed