If its back on the car, test in situ with glass on a 12v supply. You probably know this but 2 connections that reverse polarity to go up or down. Sounds like the controller isn't giving enough power. If it's just not enough power to move the window it may power a relay.

If using 4 axel stands, be aware as you jack the car with a trolley jack the arc of the jack means the jack will move inwards or the car will be pulled slightly backward. Not an issue for just front or rear but if one end is already on axel stands it can't move which can mean the car is being...

It's my understanding the rollers go in opposite direction so there is no or very little drive to the diff and therefore no or little attempt to drive the rear wheels and the vcu should be happy.

Depending how fussy you are, a decent size hole below the front 2 under tray bolts means you can get socket direct onto bolt, although it is possible to get to it bending the plastic down. You don't loose too much skin and it grows back fairly quickly. Just seen this is a fl2 so not sure where...

Scanner should show dpf in and out readings. If you intend to keep the car I would look at new dpf, especially if the last regen was 500 miles ago.

Possible not charging from alternator.

Is it manual, if so could it be clutch slipping?

Might be a silly question but did you roll them forward. Makes it quite flat.

Only with foot on brake, is it a miss fire or drop in rev as it may try and creep forward but can't as the brake is on so the revs fluctuate? Not an auto driver so only a question.

The misses ignored me one night, kept on telling me how she is ignoring me. Can't get any quiet time

I found a steam leak by looking when it's dark and using a torch. The vapour will show up more.

Common issue, I think it needs an open end spanner behind the tensioner. I've seen threads on it so keep searching.

How does it feel with engine off?

As you cured it for a few hundred miles maybe the pads are just not working well with the discs.

I've heard soft gentle braking can cause a squeel. A few hard stops now and then may help.