in mercedes benz W210, the electrics are a bit assinine as they dont do a self refresh, need software for that (easy nowadays).
The mechanicals are simple too if you follow correct procedure sequence and specification. e.g. if the manual says to tighten bolts to 15 lb/ft and then pull 90 degrees, you should follow that and not rely on andaaza.
Once mechanically sweet - connect the wiring back onto engine and drop it in the car (repair/reloom wiring as required) - connect diag tool, do a reset on the ME and EGS unit and start her up.
The battery should be on a tender (above 13V) when resetting the system, reboot car once (cycle key till K40 relay times out) then attempt to start car with battery booster/jumper fitted.
Prevent the battery voltage from dropping below 10V when cranking her up as it can make other units go cuckoo - This is why the battery on any modern benz needs to be solid powerful.