I won't show you the scratches on the rim, even with plastic on the tyre levers. Arrrgh. Pass the black marker..
I used a sharp little knife to cut the sealer which is flexible stuff. The battery connection strips are tack-welded to the battery so I put the same sharp little knife under them and broke the tacks. Cleaned up, bent the lower strip up a bit, pushed new battery into the hole. To solder the top strip to batt, I had to scratch the batt and tin it, then hold strip down (springy!) and solder it to the batt. I would sandpaper the battery and tin it before inserting next time. Smathered in a spoonful or so of some epoxy stuff. I would get some flexible stuff next time. I think there is a switch in the sensor (small rattle when you shake it) which activates when wheel is rotating to save batt when standing. Reading came up after a few hundred yards riding.
Main learning is to get dealer to take the tyre off next time, he has a good piece of kit and has not marked the rims in the past.
The sensor is not in the middle of the back rim, slight offset. I took it out the side nearest to sensor and I should have done opposite side. There is more room between sensor and safety ledge to let tyre bead sit in while remounting bead on rim diametrically opposite.
I though I might flex the tyre enough to get the sensor out after breaking one bead, but impossible. You have to free the opposite bead off the safety ledge to have enough room to work.
Bin