The battery came from the UK to SE Asia in less than a week. Replacing the battery and putting the unit together was very easy. I had bought some "Scotch Professional" clear plastic adhesive to reseal the back of the speaker case but in the end decided against using it, just in case I needed to replace the battery any time soon.
I am not certain if putting the case together minus any kind of sealant has affected the acoustics -see earlier posts. Rather than use a super strong glue, I reckon that even something like PVA would provide an adequate seal. (My first choice would have been some kind of silicone sealant but the shop only had black and my speaker unit is white, so I decided against it.)
I'm glad to say that the front plate did stick back on despite being exposed to the air for about a week. Also the speaker unit appeared largely cosmetically unaffected by its removal. I would say that if you use a hot hairdryer or heat gun set to low heat, the front plate will come off less traumatically, than it did for me and that would further minimise the risk of scratching the front plate.
In wondering what difference sealing the unit with glue would have made but without wanting to open it up again to try, I decided to carefully seal all around the join using scotch / sello tape. I did this as a temporary measure but saying as I put the tape on as elegantly as I could, I was surprised to see that cosmetically it didn't look too bad. I can't say if acoustically the speaker performs any better as a result - though I'm pretty sure the back panel is close to being air-tight. Obviously, it won't look quite so bearable in a year or so's time, when the tape turns yellow and starts peeling off. Maybe then, I'll have the courage to open up the unit and glue it back together properly but for now I'm happy. The replacement battery is giving me a few hours of mains free music and I feel I've won some kind of a moral victory by fixing it and not spending big bucks on a new speaker dock, which I really can't afford or need right now. If you're thinking of repairing these speakers, my advice to you would be: do it.