Mercedes Benz repair: It turns over and dies after new battery installed, vroom vroom, phoenix motor co

Question
My 1998 Mercedes ML320 SUV went click-click-click when I turned the key so I had my husband replace the battery (moved from AZ where the battery wore out yearly) now it turns over quickly but dies instantly--I thought it might be a kill switch needing to be reset but my old mechanic from Phoenix says I need a new key and the dealer technician here in Lexington KY thought if I left the key turned on for 15 minutes it would reset itself.  That didn't work.  I'm stuck in my own driveway and trying to avoid a tow to the dealership 20 miles away.  It sat for a couple of weeks-I thought maybe moisture in the gas?  And my husband jumped it from his car without the engine running thinking the voltage wouldn't be high enough to damage the electrical system.  Now, new battery in place, the keys still work on the locks (remote) but it won't go vroom-vroom...can you help me?  

Answer
Actually I was a techincian for Phoenix Motor Co. in Phoenix, AZ for quite a few years and I know what you mean about batteries going dead early. Your problem is generally caused by a key not communicating with the ECU.

Most likely you will need to take it to the dealership for reprogramming. When we reprogram a key, we have to use our diagnostic computer the set the program and then leave the key in the ignition for anywhere up to 24 hours. The key and the ECU both put out numeric codes (about 15 codes per second) and the key has to be in the ignition for that amount of time for the coding to sync up with one another.

You should take this to the dealership.