A1016 Keyboard

I'm using a MacBook Air (2020) with the M1 chip, running macOS Monterey version 12.0.1, and I'm having trouble with an Apple A1016 bluetooth keyboard.

I know it's old and I could just get a new one, but I love how this keyboard looks and feels. Up until a few days ago, I had been using this keyboard with no problem. But the batteries died and I replaced them and had trouble reconnecting. I tried just restarting both the keyboard and my computer and forgetting the device in the bluetooth settings, but I haven't been able to reconnect since.

Going to the Keyboard settings and trying to "Set Up Bluetooth Keyboard" hasn't worked. It detects the keyboard right away, but when I hit "Continue" it just says "Connecting..." forever. Sometimes it'll give me a message saying it wasn't able to connect, but lately it just does nothing but sit there trying to connect.

I have also tried connecting through the bluetooth settings, but while it does give me the option to connect, nothing happens. If I click "Connect" nothing happens, but if I press the Enter/return key on the keyboard a six-digit code (different every time) pops up for literally one second and then goes away, and tells me "Passkey mismatch".

I have tried 0000 and 123123 and all that without any luck. If that code popup would just stay on the screen for more than a second, maybe it would work.

I'm just kinda sad because I've been using this keyboard for a long time and haven't had any issues until now. If anyone has suggestions or has had this issue, ANY advice would be really appreciated. Thank you!