Engine harness problems m20b25

[DannyBe]

Hey guys, long time lurker first time poster. I am completely baffled by this harness problem. Any help would be very much appreciated.

I am the owner of a 11 88 325is coupe. Initially, it was auto, but we swapped it to manual last winter and it ran fine for like 2000km this summer. The initial problem occurred because the sensor coming up from the oil pan (3 pins) had the plastic cover that interlocks with its counterpart from the engine wiring harness broken. So idiot me sealed off the 3 individual wires with electrical tape and shoved it into the connector from the engine harness. I knew it was a temporary solution but completely forgot about it. Eventually, obviously, the tape stopped holding them together and the wires shorted on something, burning my first engine wiring harness.

I bought a second wiring harness off ebay (identical) and installed it. When I turned the key the starter did "click click click" and then I saw smoke come out again, from a different spot. The cause wasn't the oil pan wire anymore. The burnt wire was on the passenger side, suggesting it shorted near the ECU?

Is it possible that my first wiring harness also damaged the car's ECU? Is it my starter's fault?

Why is it not coughing into life as it should :(

Thanks in advance guys

[SmokeE30]

I would double check your starter wiring is correct otherwise it is possible that something that shorted out from the first harness issues is still shorting out, did it pop any fuses?

[DannyBe]

The fuses do not seem to be shorting (verified with the continuity tester). We also checked the same sensor from the wiring pan, since I finally bought a replacement, and this new one seems to be fine.
I will double check the starter wiring but I think it has different size of wires (8mm, 10mm, and 13mm) so I doubt we got that wrong.