Various issues, sunroof won't open, engine won't start (fixed)
 

So, as these forums are filled with fantastic information I figured I would pitch in and donate information back. I bought my first R53 last spring (I now own 3...) it had obvious signs of water damage inside, but a solid body without rusted out everything which was surprising for Ontario, Canada. Purchased beyond cheap considering the price of parts.

Well before I knew about BMW electronics, We gutted the entire car, found the disconnected sunroof drain and fixed it (thanks to this forum) Unfortunately it was the front right drain, which happily drips directly down and onto your BCM (body control module). Additionally found the roof antenna to be somewhat leaky.

We anticipated visiting a classic British car meet one morning, the car started briefly and quickly died in a few seconds. I restarted it 10-15 times without a sign of life, I then manually checked fuel, had a friend over dissected the entire car without a single sign of life. Tinkered with random things for a few days, brand new coil pack, spark plugs. Eventually finding my way to inpa to read the entire cars electronics. Immediately finding EWS communication issues, I ordered a brand new programed EWS from bmw. No fix, I then ordered a brand new programmed key from bmw which directly communicates to the EWS. No fix. On a final feat I sent the ECU out to RPM motorsports and had the EWS system bypassed. Fixed entirety

The second issue was the sunroof never worked. After confirming the sunroof opened manually we found cheap parts at a scrap yard. Replaced the sunroof motor and button which is the entire assembly aside from wiring. It never worked. I then found a generous post online which said person wired a switch into the fuse panel. This switch was to complete the circuit to turn the sunroof on within the computers. As the BCM was short corcuiting the sunroof connection from getting wet prior. Essentially you turn on the switch to turn on the sunroof circuit, open or close the sunroof and then turn off before it short circuits. If you leave the switch on your unable to operate the sunroof after a few minutes.

I guess in a round about way, the proper way to solve this was would be a new programmed BCM. But without experiencing things you never learn. Thanks to these forums and others for the help!!