Traveasy

Got back from 5 days of not driving. On return battery was dead. Service guy jumped it and replaced key battery (essentially dead). Last night on 2 separate occasions car started randomly making an alarm like very loud sound. Sound stopped when I opened garage (I thought it was gas leaking from the house gas tank). Turns out its the car I realized when I parked at the grocery store.

How do I stop this from continuing?

BenzV12

I ain't expert but I would remove the metal key from the key fob and lock and unlock the door with that metal key .
That trick worked in my previous car (I used the key not the buttons on the keyfob) but MB is different for sure