I also think this is an AAM problem, very common after replacing a battery. I don't know what to do except get another key. It usually is caused by trying to start the vehicle with a very discharged battery, and the AAM module decides the key is bad. As I understand it, you only have 8 keys total that the AAM can use, so if you haven't gone through all 8 yet you can go to the dealer and get another key.

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Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C