No connction to dme, crankar No start

[Wingee]

Hi fellow bimmers, im writing here cause I have a problem with my E90 330i 2006 after removing the engine and transmission from the car. With everything back in its place the car wont start but only crank. Trying to diagnose the ecu/dme is impossible because I can't connect to it. The dme relay clicks as they should when turning ignition on and I can still connect to cas and the rest of the cars modules. Bought a second hand ecu/dme with identical labor but still No connection leading me to think its something else then the actual ecu/dme. Note that i didnt program the new dme to the car, i only tested if i could get a connection to it.
I did miss a ground cable when first trying to start the car which sits right below the white box containg the ecu. Although this was quickly fixed so i dont think that has something to do with it? Also i dont have access to inpa so i have only used 2 obd scanners that have worked before.
If u guys have any idea or suggestions please let me know! Im getting sick of my once beloved pearl

[328 Power 04]

The next step here is to get a multimeter and check for voltage and grounds on the dme wires. You will need to use wiring diagrams.

[Wingee]

I have checked the 2 relay for ignition and dme and they both feed the correct current. Will check the main wires on the dme tomorrow!