The ML key transponder problem is VERY easy to check! TURN the key to the on position & wait 5 seconds then try cranking, IF the starter works then the key IS sending a signal & isn't causing the problem!
IF the starter doesn't work (after the 5 second wait) then the KEY or transponder is the problem!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator