[goodacheez]

I bought a 2011 F25 X3 xDrive35i with 188k miles 4 months ago. It had oil leaks everywhere so I didnt drive it much before doing some much needed maintenance. I replaced: the valve cover, valve cover gasket, OFH Gasket, oil pan gasket, oil cooler gasket, air intake manifold gasket (with ECU gasket), belt tensioner, idler pulley, turbo charge pipe, new windage tray, ignition coils, spark plugs and 4/6 fuel injectors (cylinders 1-4). After all this work I primed the engine by cranking it and measuring oil pressure.
When everything came back on it was running fine with a bit of a rough idle. One of the things I tried to fix this was tightening the v-bands on the new aluminum charge pipe. I learned I shouldve unplugged the battery first because the charge pipe acts as a ground point. I saw sparks as I was taking my socket out between the alternator and my socket extension.

 The test drive after the short seemed to go well until my car compelety died. I was able to jump start after a long time of my friend hooking up his car with jump wires so i assumed it was the battery. It died soon after I got it to turn on. I got a ride back to my house and I took a newer battery from another car and i was able to get it back home. This battery was from 2019 so it was ~4-5 years old at this point. it made sense the short had eradicated any capcity for the battery to hold charge. 
 I jump the car in the morning since it was slow to turn over (even with the battery I put it in). I go and buy a new battery the next morning and it turned on like a charm. After a few good miles, I hit WOT on my way home and everyting felt great, until it wasn’t. A couple miles down the road my car exhibited the same behavior as when the battery died the night before. power cut off and the car was in neutral. Only this time it never cranked again.
My friend came to try and jump me and the car would just “click” no crank, no start. eventually i started seeing smoke coming from the starter area. I had the vehicle towed home since i was blocking traffic pretty bad. 
 I found some fuses were blown from the charging system. I replaced those and still nothing just “click” when I hit the start button. I did find that one of the fuses i replaced was a 20A and the diagram says its supposed to be a 15A. Someone fucked that up and probably why the starter burned a wire. 
 I inspected the starter and the fat wire is definitely burned but nothing else looks burned out. So maybe it was that the starter couldn’t turn the engine? I went to turn the crank manually and the engine wont budge… not one bit. spun bearing? it hadn't knocked once before, did it somehow lose oil pressure? what should I check first?


[pungo]

Welcome to the forum...
After you performed all the work, especially the OFH gasket, did you prime the oiling system prior to starting the vehicle?

[goodacheez]

yes i primed the engine after all the work since it was all done at once! I gave it three ten second cranks with 30 seconds in between. the engine held compression and reached around 50-60psi.

Thank you for the fast reply!

[pungo]

I was going to say to use ista+ to scan for errors, but if the engine won't rotate manually, there must be some type of mechanical restriction. Unless there's a valvetrain issue, the oil pan needs to come off for inspection of the bottom end bearings. Did the engine sound normal when it was running?

[goodacheez]

the engine sounded healthy when it was running. had a bit of a rough idle and some codes indicating it was running rich. once i tightened the charge pipe v-bands the idle sounded better.
After that codes that the boost pressure was too high came up. Also electrical codes saying there was a lot of components that were under powered. The electrical codes went away as soon I replaced the fuses and main relay.
im reading codes with an ancel-bm700, as i have not been successful in getting ista+ to run.

[Weslsew]

Originally Posted by goodacheez

power cut off and the car was in neutral. 


when you say power cut off, do you mean the engine shut off or you lost electrical power or both? this sure sounds like an electrical issue. I think you fried your alternator which explains why the car would run off the second and third batteries for a little while until they died.

Then when you tried jumping it the last time, you may have had enough power to engage the starter but not turn the engine over. You may have burned out the starter with it stuck/still engaged on the flywheel, which would explain why the engine won't turn manually. Have you tested the starter with a multimeter? Pull the starter out and then see if you can turn the engine.

[Opie55]

^ This. The odds of two major issues (electrical failure and mechanical engine seize) at once are remote. You probably need a starter and an alternator and maybe some wiring. But step one is taking off the starter and trying to turn the engine. Loosening the plugs will allow it to turn easier.

[E36M3]

I would suspect your ground strap from the engine to the body. Reason is you should never have to disconnect the battery to tighten a vband clamp. If it was serving as a ground then your actual ground is bad and needs to be replaced.