I would like to know what could have caused CA to stop working.

• My 2 keys only Unlock/Lock doors & pull convertible top down.
• They don’t do keyless start, put top back up or unlock/lock via keyless entry anymore.

Going Mid 2020 I started to have problems with one of the belts which sounded like a knocking when hitting gas but got quiet when idle. So I stopped using it knowing how COVID was ganna take a while. Finally got around to having a mechanic fixing it after a couple of months of no use. Being that it’s my first car I didn’t realize it’s a good idea to disconnect battery during its dusting days. So after a few days my mother tried using it & left her stranded on the freeway. Battery related, autozone found out it wasn’t holding charge so bought a new $200 premium battery.

After installing I didn’t realize much of a difference, a week later I realized I don’t have comfort access working anymore. Didn’t really mind because I usually just use my keys to unlock n start car.

Months later my car just doesn’t turn on. Everything on dash is dead, no sounds or anything just a dead car. Keys didn’t work either despite me thinking changing to new batteries might help, so had to use key in keyhole every just to unlock & lock car.

Checked fuses & F21 was blown.

Upon disconnecting that fuse though, (while key was in) the radio started. The car turned on fine when I went to try the button.

So I’m confused, is that why my comfort access doesn’t work anymore?

F21 (Lock Symbol) - YouTube video says Central Locking

Its my first car btw (motorcycler for years before my first car) so don’t know much but can learn & mess with things by myself.