I had a problem with my Plus after removing the Landsurf wiring, the board wouldn't turn on. Suspecting the BMS because the board would turn on if the battery was connected directly to the controller.
I decided to check the wiring harness with an ohmmeter first, and found a open circuit on the small blue wire.
During a "wiggle" test, the blue wire made connection, peeling back the shrink wrap, I found a kink and what looks like bare wire. This kink looks like it was there from the factory waiting to break.
After repairing the wire, the board still wouldn't turn on, perhaps the arcing of the broken wire fried the BMS.
Anyways, I decided to zombie the board, but with improvements.
-Made a 14s2p battery from a broken Ego 5 amp battery
-Used a printed Xr battery box(more room)
-Used a small BMS for charging only
-Rewired the controller to be able to use the original charging port
-Used a "loop key" instead of a electronic antispark switch
Advantage of 252 wh instead of original 130wh, almost double the range.
Downside, voltage percentage doesn't work, but can still see voltage in the app.

I was thinking of using cheap bearings on a Pint, but was lectured by a local Onewheel service/dealer. However, after more research, the biggest difference in bearing are the seals, cheap bearings have seals the you can actually see a gap if you hold the bearing up to a light.
You can actually see the balls through the gap.
Not wanting to spend over a $100 for bearings with a laser etched "logo" I opted for quality Japanese bearings from Koyo, I didn't trust SKF as there are counterfeit ones.
Koyo, Nsk, Nachi are good brands. Look for 61907 2rs (6907 2rs).

The previous owner tried to install a extended battery and probably did the plug in sequence wrong and got an error 16. Once the battery is plugged in, the Pint would say on and flashed the error message and could not be turned off with the power switch.
I've since removed the defective mosfet and replaced it with a higher amperage one, however I noticed the charge connector gets pretty warm while charging. I think this a known weak area with documented failures. Picture is of repaired and tested BMS.

Woohoo! Fixed my first Pint bms... bought a broken Pint for $525, I was going to modify it with a Raiden 7 vesc, but decided to play around with it, determined the BMS was bad. I'm not good at electronics, but I can use a ohmmeter. After doing some basic troubleshooting, determined one of the switching mosfets was shorted and passing current without the power switch. I had a n channel mosfet with roughly the same specs as the original(it was for a Plus) temporarily soldered it in, and it's alive. Now don't know wat to do with a stock Pint.

I made a custom XR/PLus board with extended rails controlled with a Raiden 7 vesc. Printed controller box that I had to modify, there is a version of the box that doesn't need much modifications. Stock XR battery for now. Rides really well, but still needs a bit of configuration tweaking.

@Lia
Getting close, I'm sure you're on discord and in the last couple of months, big strides have been made in the Vesc firmware, not by me, so much I have a hard time keeping up. There's a wizard on discord that complies and changes the code a little at a time to come up with new firmware. Right now I'm trying "soft start" when the board engages softly like a OW, but still a few issues to iron out.
Yeah, I think I've seen your Pint rebuild on line. You had to print a controller housing? How's the rebuild coming?

I bought a Pint battery box and controller housing combination with a shorted out controller. I used part of the controller circuit board and wired up a Raiden 7 vesc to it. Installed the reworked module in my spare Pint, programed the vesc and made a rideable board. The battery is stock Pint. I was able to to reach 23 kmh with no pushback. I didn't want to push it further, trust issues with new builds. Still more fine tuning to do.

@nraney
There are used V1/Plus(same) bms for sale on Facebook Onewheel parts groups, ranging from$150 and up. Repair services are also available on the those pages also.
Extended range batteries are available from Chibattery and JWbattery that eliminate the stock bms with their own bms and switch. Down side is that the app doesn't work.

Are the V1 and Plus BMS(s) interchangeable?

@Zocchi
Sumo wrestler foot! Ice that down and get better soon.