That's correct: the BIOS was corrupt; the machine had no display at all, so no way to enter the BIOS menu or "boot" an OS. Other Lenovo laptops have a recovery

That's correct: the BIOS was corrupt; the machine had no display at all, so no way to enter the BIOS menu or "boot" an OS. Other Lenovo laptops have a recovery mode (Fn+R) where some bootstrapping firmware would flash a BIOS from USB, they neglected to include that feature in the (presumably lower cost) Flex lineup. Some folks out of support went as far as desoldering the EPROM with the BIOS and hooking it up to a flash programmer, to get the laptop unbricked. I realize they have a lot of different models and probably a limited test matrix, but it's still unforgivable to push a forced update that bricks the device to this level (and until that happened I didn't even know OEMs can push BIOS updates over Windows Update, probably because most of my machines are custom builds).