Distinguishing frozen car locks from dead key fobs

https://delta-wiki.win/index.php/Distinguishing_frozen_car_locks_from_dead_key_fobs

When your key fob doesn't unlock the car, it's easy to assume the battery died, but in freezing weather, ice inside the lock can be the real culprit. The fob's LED may still blink, and you might hear a faint click, while a frozen lock often feels physically stuck with no response at all. Try warming the key or using de-icer before changing fob batteries.