Reading between the lines, I think you've confirmed what I figured I had to do to replace the cells in my X230 - apply voltage across each of the cells as I swap them out, so the chip doesn't lock down.
But now I'm wondering if I can simply get a busted X220 battery to repair and use in my X230. The first search result says that it fits, but the X230 won't charge it due to DRM crap. But it also mentions a modded BIOS to get around this, and I'm running coreboot, so it seems that avenue might still be open - assuming it's really the "BIOS" and not the EC (embedded controller) chip checking.
BTW is gutting power tool batteries really a practical way to obtain reliable 18650 cells? It seems like that would be an expensive source, even on sale. But I admit my experience is with Dewalt 20V, which have their own premium. I figured I'd be hitting up the vape community to see their recommended sources when I got down to it.