Distinguishing frozen car locks from dead key fobs

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

On a freezing morning, when your car key won't turn or the doors won't unlock, it's a frustrating gamble: is the lock actually frozen or is your key fob dead? A dead fob often shows no lights or a very dim, slow blink, while a frozen lock typically makes the key go in but then it won't budge at all. Try warming the key with your breath or a lighter, or use a de-icer spray; if that works, it was ice. If not, and the fob still gives no sign, it's likely a battery issue.