Nope, no signs of life with the battery removed and on wall power only. I believe the battery was not to blame, but something went wrong that caused it to also drain the battery. I will check the battery anyway and report back if I find anything interesting. Thanks for the helpful link.
I found the fuse, but it wasn’t blown 🥲 I’ve looked over the board, and watched some repair videos but I haven’t found anything. I’ve called it dead now.