OK, thanks to a comment in an earlier topic by Photon [for which, tyvm!], I realized I’ve been doing the sequence wrong.
It’s necessary to FIRST press the power button until the LED lights up, release it, and only THEN hold the Volume Down key until the image on the µSD starts.
I had been following this in the Tips & Tricks wiki, but the problem (for me) was this phrase:
… during boot, hold volume-down
which doesn’t make it clear that you have to release the power button before pressing and holding the Volume Down key.
So anyway, I’m on the pmos_continue_boot screen again, with nothing happening, apparently:
Continuing boot…
_
