I think everything you need to know should be in this thread.
I’m an ocean away from my TI Desktop at the moment, but my recollection is the battery replacement shouldn’t be too hard for someone who is handy with a screwdriver and is comfortable with PCBs.
I think the AURA plugin is the preferred one these days for everything including preset management (which is still a bit fiddly, but always was)
Mods: if / when you merge this thread in, please just delete my post. It won’t add anything within the context of that thread.
Finally: congrats and welcome to the cult club.