“Trying to start the car and the battery in the key fob went out and the car would not start.”
I just bought an Autel AP200 code reader. No engine light or anything, just wanted to have one. I scanned my car and there is one diagnostic code, for a low battery in my key fob.
Reading up on it, the fob reports its battery condition every time it’s used. Replaced the CR2032 battery and cleared the code. That code reader saved me from going thru what you went thru.
A lot of later model cars that use the proximity fob have a spot in the center console you can place your dead fob to start the car. Likely an RFID chip in the fob that the car can ping.