Hello and welcome! I'm Billy and i will assist you with this.
My apologies for the delay, thank you for your patience.
Eventhough the key issue was sorted, i will include the details on your key's operation, battery replacement etc.... so you keep with you for future reference:click here for details
As for the starting problem, it could be the starter, the wiring or the ignition (command...)
In your case, the most common problem causing this, would be corrosion at the connectors of the ABS
/BAS control unit. This problem is so common, that MB had to release a technical service bulletin. I will include the bulletin, which has the details necessary so you proceed accordingly.click here for details
Thank you for your trust! Get back to me if you need more assistance...Thank you in advance for the positive rating...