EBD is brake distribution, its joined with the BAS and ESP modules (If equipped) which do not prevent startup. The only item that prevents startup is the DAS (Drive Authorization System) if equipped - however the dash should flash start error on this fault. or no signal from the engine position sensors or extremely low fuel rail pressure. Call them up and ask for a log prinout of the faults they found. There is a relay box that can show up such elusive faults, mostly it causes the ABS pump to work overtime and the brake system warnings remain on. On a W210 and similar era road cars its called K40 relay module.
If your vehicle electronically turns on and if mechanically the engine can push out at a minimum 300 psi compression, and the fuel rail holds at least 4700 psi pressure, your cam and crank are giving correct time signals and you have good fuel - the engine will fire, otherwise check the injectors. they maybe clogged or bad. The only way to test them is with a MB diag tool or a test bench that can run them.
The ECUs themselves are not the garden variety ECU that you can find anywhere and neither can they go bad on their own they are pretty well protected electronically.