Jumpstarted my 02 CLK 320 and it started. Put car in reverse, was fine. Turned heater on and car died. Havent been able to get restarted.

check the battery. Make sure it is load tested and that it is the correct battery for your car. Some benz's require pricey batteries.

Go to the local car parts store with your battery to test it. They no doubt will have a top , not so pricy, battery it you need one replaced. Also have the alternator tested if the problem persists.