Just thought I would pen a couple of lines on this. In essence I bought x3 spare batteries for the key fob and then put them in the tool box until the other day. so two days ago I decided to fix the fob. In short I got the plastic outer apart fairly easily starting at the keyring end with a flat bladed screwdriver. I then removed the old battery with a soldering iron only to find the new battery was not a exact replica.
In short the two connectors on the new battery were further apart than the spaces on the PCB. I managed to get around it in the end by cutting the connector from the old battery and then snipping the connector itself to make it small enough to fit into the (+ve/ -ve slot) on the circuit board.
So make sure you do not buy the wrong battery.
It worked following my bastardization and I stuck the two plastic sides back together using Gorilla glue.
Apologies for the labelling but the replacements connectors were fixed on the battery too far apart so I snipped the thin metal strip from the original batterywhich can be slid under the connector on the new battery.
I think the way you did it is pretty much the only way as a replacement battery with the terminals in the original orientation is supposed to be impossible to find. Regarding opening the fob, you were able to just pry it open without any cutting?