^ Yeesh!
Good luck man!
Would seem both issues would be covered or potentially covered (idk if actual batteries are, but you have evidence or at least recollection of a light staying on) by the bumper to bumper warranty.
If they "can't replicate" the issue either you're lying ( you not, why would you subject yourself to going to the dealer for repairs if there wasn't an issue? lol) or they "didn't notice" it.
If they try to charge you, maybe suggest a test drive WITH the tech so you can point it out.
Been there, done that.
Had warranty work on a trans a few years ago on my company truck. The service guy actually told me, hey it's going to shift hard for a bit on you until the transmission re-learns.
I leave, and same symptoms are present as before I brought it in.
Dude actually was pre-emptively trying to pass of a bad repair job as trans re-learning....
another month later it came back with a new transmisison. 2 attempts to repair the original one and a third try by replacing the whol etrans.