Did the airbags go off in the accident? If so then maybe the SRS module has disabled the vehicle because of that, it happens to plenty of petrol/diesel powered vehicles after a crash.
Need to clear crash data from SRS ECU before vehicle can power up, it doesn't even worry about missing airbags, just ...

Have a look at 280 size relays, I wire up all sorts of conversions with these and don't have issues other than when you over do the current draw, 25a is to much for the pins more than relays
Lots of size options and open layout plan let's you do what you want with the number of fuses or relays ...

It would be a awesome motor in the future but I'd be pretty certain it will have VW's component protection enabled as soon as it's powered up outside of its original vehicle so id say it's probably going to be easier long term to do the same as the tesla m3 and make a new board for it unfortunately ...

What about something like this?
https://aicontrols.co.nz/rd1-canbus-dash/
It's a bit cheaper than most of the aftermarket dashes and would need to be reconfigured for ev usage, but might be easier than making your own from scratch. There is a raspberry pi dash out there as well and it takes ages to ...

I've other one of these for my conversion when I get back onto it one day, it all looked OK quality

Maybe or find some different canbus wires in the vehicle, try at the heater module or back of radio

I have had luck with disconnecting modules with vcds in VAG cars, with Fords I have only ever tried turning features off inside modules, it maybe possible with Forscan or the dealer tool but otherwise like Tom said you'll have to broadcast the canbus signals the other remaining modules are expecting ...

Sorry to see that happen, I'm not the best repair guy out there but would be saying it's probably a bit past it now, quite a few burnt bits there, multi layer board and it probably relied on it all being nice as a heat sink also?
Any idea what actually caused it to fail?

In the car I only use deutsch connectors, 4 pin dtm for can as it's a pretty common thing across aftermarket ecu installations, then dt connectors for everything else

It could possibly be going into component protection mode after a certain time, vag stuff sometimes has a time delay built in so that it has some functionally until the time limit is reached then it shuts down until coding has been done to link it to the car.

Don't get started on "normal" bolt sizes, Japanese cars always use 10,12,14,17,19mm bolts, normal euros run 10, 13, 16, 18mm and then you have the American sizing which is usually in-between metric and imperial because they can't make up there minds.
Now it's not any easier as they go between 6 ...

Looks like a common fuel injector connector.
Bosch US car type
https://msel.co.nz/uscar-2-way-fuel-injector-connector/

What about a model 3 front motor in the back, that should hang behind the axle line I belive. Probably a bit less power though.

I do a bit of factory vag coding work and I wouldn't think it'd be possible using rosstech or odis software sorry, however maybe with vcp if you were good at using it otherwise do what they do with the engine ecus, by reading the eeprom data and modifying it, not what I do and I know in the later ...

There is a honda accelerator pedal sensor that works nicely with most older style cable setups, have used these in boats and cars with a e throttle conversion before, out of lots of different Hondas so cheap at the wreckers yards.
https://www.amazon.com/Genuine-Honda-37971-RDJ-A01-Accelerator ...

VCDS is also a good VAG scan tool but both ODIS and VCDS only talk to VAG cars, if your running BMW modules you could also use the BMW scan tool or one of the many specialized aftermarket ones or could look into a general aftermarket scan tool but you'll probably loose out on some of the information ...

Hey it probably depends how you want to control the motor and what you want to do with it.
If you want to go racing or lots of quick driving may be best imo to go with the model 3 motor, as its better cooling and efficiency will allow more performance over a longer period of time. I have gone this ...

Would it be ok to use un fused milspec wire? Something like 24 ga cable? The milspec wire should melt and not hurt the insulation so no fire risk

So far I have only worked with a couple of aftermarket pdu's and generally you make it up as you go along. Usually your trying to pick up data from engine ecu's on their factory can outputs.

What sort of spec vehicle? I have a 2007 passat manual diesel 4wd or a 2009 A4 fwd cvt I can get logs from this weekend if you give me a good description of how to lol I have a working savvycan as well.
Both cars do have engine fault codes but abs and traction control works fine in both

It doesn't quite work like that, you have to have a battery in the alternator circuit, it's there to smooth out the current output and help stop any surges in current from the alternator.
If you end up running a vehicle with no battery the alternator doesn't get a good reference of system voltage ...

For anything VW I go onto https://erwin.volkswagen.de/erwin/showHome.do
Then enter the chassis number and download all the wiring diagrams, not sure about signal info but it has all the right diagrams, €7 per hour but I've managed to download full vehicle diagrams in that time

Looks right to me, not sure the Z or A would mean anything but their definitely in the picture

Yup was exactly my thinking when I saw one for quite a cheap price, not sure I'd it's good or not but about as cheap as I'd seen them and perfect to get my project started

What about buying a brand new one that is capable then just get it coded into the vehicle by someone who specializes in retrofitting or modified coding of bmw's? The same sort of way when people upgrade their radios or other modules, it usually here in New Zealand requires someone a bit more willing ...