Grim55

Hi,
I have read some threads with similar issues, but it seems that my problem has not been discussed yet.
I have an e61 530d 2004. I had an increased emissions error appear and diagnostics showed several DDE errors - MAF (which is recently replaced), starter (which seems to work fine), fuel heater and generator. Since the new MAF and everything else seemingly working fine and the car was driving fine, except the EML light showing, and all errors being related to DDE, I figured out it must be some problem with the DDE, perhaps some plugs that can be cleaned or something like that. Anyway, I thought checking it out cannot hurt.
Now I got a much bigger problem. The car does not start anymore. It cranks, the fuel pump is making noise, all fuses are good, but it just does not start. Checked again with ISTA and it shows 441C, 442C, etc. six errors for all six injectors activation. The ISTA procedure suggests checking injectors (which I am sure are fine), lines and plugs. I have checked all plugs severally and they all look fine. So the only thing I feel is left is the DDE itself, which I might have somehow broken when opening up and checking for corrosion. Visually it looks fine as well and there is no corrosion visible.
Has anybody experienced issues with DDE and did you have the same symptoms? Anything else to check before concluding that the DDE is to blame? And if it most likely is DDE, what to do next? Is there a point in ordering new/used DDE from ebay? I have ISTA, but I have not coded anything yet, so not sure if that is something I could do on my own.
Anyway, any help, feedback and suggestions are much appreciated. Thanks