The ease of opening the shell was quite inconsistent for me, my left bud opened easily after gentle heating then using a thin metal sheet which was supplied with my battery for this purpose.
My rights shell however refused to open after multiple heating sessions, causing some scratching damage to the shell while I became desperate over an hour worth of repeated attempts.
However, by using some GENTLE pressure from a glue clamp, the shell popped open. Because this immediately causes the pressure to drop, I didn't risk crushing or severely distorting the shell.

After destroying my first left bud connector (battery removal mishap), my second left bud now has a new battery and appears to be fine. (have to give it some longer testing time though).

I made it this far. Reading about having to use some force, I though using needle-node pliers (Leatherman wave) would allow me to securely grip the battery and take it out in a controlled fashion.

I slipped and the pliers crushed the connector on the board beyond repair so be warned.
Using a metal pointy object (sharp tweasers, same as @alana48457 ) I was able to get under the battery easily and wiggle it loose. Sure a small risk of shorting though, but I think for this section, it may be okay.