I bought a Surface Pro 4 - Update

So I posted a few weeks ago asking for opinions on the Surface Pro 4, trying to decide if I should pick one up and slap Linux on it.
Opinions were.....mixed.

I got a decent deal on one, and that's partly why it's taken me so long to post an update. It was cheap because the previous buyer had returned it to the seller claiming that there were power issues. The seller said they hadn't encountered said issues in the hour or so of testing they did, and I call fucking bullshit!
Once powered off or restarted it was taking up to 48hrs before it would grace me with booting up. And usable time ranged for 15mins to an hour before system lockup resulting in either a freeze until battery run out, or immediate system shutdown, and another 12-48hrs wait to power it up again. Obviously this is suboptimal.

Part of the issue, possibly unsurprisingly, was windows and the stripped down BIOS. After turning off secure boot, turning off the "battery saver" mode(restricts charging to 50% of total capacity) and scrubbing windows off the drive like a crusty booger...things have improved. I'm still unable to restart the device, restart powers down, but no power up. Wait times to power up again went from probably 36hrs average to 2hrs average, and if I just don't turn it off, the system is stable.

My time with Nobara on the surface has been really enjoyable, everything is just stock, I've not wanted to muck around too much and get attached in case I can't figure out the actual root cause of the power issues.
As such, not really much else to report other than Nobara running well, and pretty much everything running as well or better than when windows was installed. Touch functionality works slightly differently in Nobara than Windows, but that's not really a bother for me.

If any of you greybeard wizards has any ideas on what might be happening with the power cycle issues I'd appreciate some suggestions. I think it may be a battery issue, but I'm waiting on a hot air station to be able to open it up and have a proper look at it's guts. Doesn't seem to have anything to do with temps, that was my first thought but that didn't pan out.