So MINI is back together but won't start. Key in the on position acts like low voltage. Battery is new, but I pulled it and have it on a charger tonight just to be sure :-/ Either way, video below, ideas welcome.

 

Not sure what you did but check all the ground points - almost every time someone rebuilds, replaces anything and has this issue its the ground point right near the passenger motor mount

 

Yup...
Grounds...
Most OVERLOOKED thing.....main one is by the motor mount ..looks like a cable...
Then various others...mostly brown wires in looms...terminating on bolts...like the ones by the front hood latch on the passenger side by the bumper.
With DC, bad ground = low or no current flow, and high resistance...
A $10 OHM meter from the store is all you need...works as a voltmeter, etc too!!

 

That was my first thought, grounds. I physically double checked them (strap at the battery to the fire wall, strap on the motor mount, and the two side boxes with the looms). I was tired so I didn't pull out the voltmeter last night, but that's the plan for tonight.

Are there any others in the engine bay that I might be missing? I'm pretty sure the diagram I found only identifies those. I did find at least one other thing hooked to the body on the driver's side. I figure I'll pull em all again and scuff em, and if that doesn't work stress test the battery.

 

Its making all the right noises in the car - did you unplug the ECU or starter for anything you did? There is A HUGE line to the starter...but please remove battery cable before checking it.

One other thought -- but I dont think it would click like that if the clutch switch wasn't depressed or is broken... you wont be starting the car.

Then double check the battery cable.

 

I did unplug the ECU since the battery box was all out. I'll be making sure the harnesses seat properly when I put it all back together again tonight. I didn't mess with the starter, but I'll check those wires for continuity too.

To be clear, I'm not trying to start the car in the vid. The key is just turned to the on position, then I rotate it back to the acc position and it isn't quite as freaked out.

 

Interesting - not sure what that clicking noise is then...I've never heard it but if I had to guess its some sort of relay going off...repeatedly

 

Sounds like a dead/weak battery with clicking from the cluster....low voltage.
try jumping it

 

Well, I double checked the grounds and also put the battery on a nice charger. So I can't say which thing fixed it, but it runs :-)