2010 Mercedes ML350 starts when it wants to. Battery fully charged and Alternator in working order. When turning ignition to on position, dash lights do not always turn on. When engine hot and you turn off, it will not start again. If you come the next morning, it will start. There are 23 computers on this car. Mercedes with there proprietary wisdom, chose not to label the inside covers of the fuse and relay boxes so it is not easy to determine what goes to what system.
I’d start with cleaning and tightening battery and ground cables, if that doesn’t work I’d move on to the ignition switch.
Welcome to the forum.
I have cleaned terminals and tightened. The ignition is working
If I let battery go dead and try to start, the dash lights turn on the way they are suppose to. If I jump start with another battery, the motor will start.
Get the battery load tested
I have. Guys the battery and charging system system are good. Somewhere in the system I have an expansion and contraction (heat) issue affecting overall operation of the starting system