[NiLuJe]

I've never encountered the KOReader issue myself, but the "one pixel left in the scan bar and then nope" situation vaguely rings a bell. I've only *very* rarely managed to reproduce that, and generally the device will deadlock soon after because it turns out it's one of the wifi module that wrecked the kernel on unload. (And I've generally been doing some fairly untoward things to the device before to get it to this state ;D. Plus, that was on the H2O, which is generally much more finicky than the Forma.).

Most of the time, the "wonky wifi" symptoms on a warm custom nickel restart are: scanning's just fine, my preferred SSID is on top, but @ 0 bar, and the initial connection attempt takes a while, then fails. Usually fixed by killing wifi, and retrying from the Settings menu.
When you're extremely unlucky, that wipes the WiFi password (although this seems to have gotten better in recent FW).
(And, for shit'n giggles: if I drop nickel from this state before attempting to get WiFi up, KOReader will connect on the first try with no visible delay. And then restarting nickel might get WiFi working with no extra shenanigans. Gremlins.).

That's just as another data point, this is obviously not what you're seeing, since a factory reset, will, in fact, fully reinstall the original FW that your device ran OOB. So, if it's still broken there, that's potentially not a good news, and I'm afraid I'm out of ideas?

(But at least it tracks with you consistently being able to reproduce that on cold boots even before the factory reset).