Hi, I'm a Bose newbie. I bought an old bose sound dock. It works great when using the mains opera supply but won't charge. The light behind the speaker grille isn't doing anything. I have partially dismantled it looking for the battery but can't see anything which looks like a battery in there. The stuff on line is showing the later model with the battery attached to the back on the unit which seems to be a similar but later model. Help please