1985 BMW 5-Series 535i e28, White with Tan interior

I bought this in 2011 and have no knowledge of its care before us. Under my husband's care this beemer has had regular oil changes and any needed repairs. I trained two children on this car and then sent it away with them to college. They came home, got jobs, and the more local child kept the car for his use. That lasted another year. It was left with us when he was driving home for a visit, sometime in 2018, and saw an oil trailwhile traveling down the freeway. He pulled off the freeway and got it towed home. It seemed that the oil leak wasn't crazy and happened only while the car was running. Plus it was easy to just add oil. So it got drove many more times for local trips, no more than 5 miles one-way. Eventually it was decided to not drive the oil-eating machine any more.
Fast forward to now: The car has been sitting for well over a year. It was time to decide whether it should be put back into use or sent to a new home. Hubby charged the battery, changed the oil, and tried to start it. It cranks and cranks but never fires. He tried spraying starter fluid, then knocking relays (in case they were stuck), then cleaning fuel pump relay connections. That exhausted our skill sets. We don't know if it is a no spark or a no fuel problem. We live in a rainy place and probably did the car no favors by letting it sit out so long without starting it occasionally. Please expect that it may take a LOT of troubleshooting to figure out why it isn't starting.
Things that we know are wrong: Oil is all over the engine; it cranks strong but won't start; the odometer does not work - AT ALL - in fact it always looked like someone had tampered with it before I purchased the car (see bent odometer needle picture) and we believe that the miles are around 300,000 based on calling a previous owner and extrapolating what we put onto the vehicle; there are cracks in the dashboard and the back bumper; the passenger-side rear window is blocked from lowering with shims because it won't readily come back up after you lower it; cosmetically it has issues, such as that basketball bump on the front passenger side, the missing trim on the passenger door, and many other places where it shows its age. We didn't check lights, blinkers, radio, etc.
Major things that got done (based on my memo notes in Quicken): Resonator and muffler in 2011; driveline in 2011; tierods and alignment in 2012; ignition repair and alternator in 2014; rear axle boots in 2017. There are several minor repairs.
There is a gray push button added to the dash with the descriptor of 'engage warp drive'. As a temporary fix and before the ignition was repaired in 2014, that would start the engine. It utilized some jumper trick for mechanics to start the engine from under the hood. It has now been disconnected. This can be seen in the steering wheel picture.
Feel free to ask me any questions you want and I or my husband will answer as best as we can.
**Revisions 07/15/20 - took off picture of VIN sticker and added picture of engine. Changed last word in paragraph 2 from firing to starting.Inserted paragraph 5.Retook picture of wear on steering wheel to show push button described in paragraph 5.