So my 04 S211 OM648 isn't starting, cranks, but doesn't start, read the codes on a Delphi system and it gave me a cam position sensor fault, no problem, new genuine mercedes cam sensor in, no change, read it with a launch system and it gave me a crank position sensor fault, okay, no problem, fitted new crank sensor (china special this time) wouldn't start, disconnected and reconnected ECU and fixed, for precisely 1 week it worked flawlessly, started 100+ times then back to crank no start, started more in depth diagnosis.

Reading the crank sensor with a multimeter I'm getting 630 ohms at the ECU connector, which according to autodata is perfect, at the cam sensor I'm getting 0 ohms between the connector and the ECU connector on all 3 connectors, 5v on pin 1, 0 ohms to ground on pin 3. Also while cranking the Delphi shows 170-250rpm

Still crank no start and giving me cam/crank sensor faults depending on what I'm reading it with, disconnected battery for 12 hours, disconnected ECU several times, cleared the fault several times, I'm at a loss, I'm leaning towards ECU fault but that seams extremely unlikely, and I dont think the wiring loom is at fault as it's giving perfect readings and I can't find any damage to the loom where I've looked near the connectors.

Getting frustrated now 

Dead OM648