2000 Mercedes benz compressor 320


my key fob died. I replaced the batteties and fob works great, however the car won't start now. I don't know if this problem is related to the battery change or not. there was a red light (icon) that appeared on the far left side of the dashboard however I am unaware what it alerting me to. I checked all possible fluids, they're fine. can you tell me why I cannot get the car to start?