The correct way to get to recovery is to power on while holding volume UP. Not down.
(Then, when the "No command" shows up, press and hold power, and again tap volume up to get to the menu).
Well, details matters. Thank you very much.
Right now, even if I do a shut down, during which I unplug everything, the Astro, weirdly enough, spontaneously boots again, but if I do a shut down and holds volume up until it boots again, I get the "No command" on the external screen. From there I can hold the power button and and tap volume up to get to the recovery menu. I haven't yet ventured further.
@Daniel W: Damn, sorry to hear you've had such issues!
I recall kinda similar behaviour with my Cosmo (prior to installing multiboot?), where if I held the Esc button for too long when booting it up, it would boot into Android but with the screen disabled - I take it that it was then booting from a secondary boot partition which had something wrong with it. You're not doing that, are you? In my case, iirc, the screen was active during the bootloader, but turned off after that - does yours display anything at all at boot? (it doesn't sound like it)
I wrote up instructions for entering all the boot modes in the wiki. Does booting into any of the other modes show anything? Does it display your charging state when it's turned off and you press Esc?
Well, at the moment, the Astro spontaneously
turns itself back on a few seconds after a shut down (I'm not doing a restart and it says "shutting down" while doing so), even from the recovery menu. As far as I can tell, neither the Escape key nor the power button appears stuck (as they both work normally once the Astro has booted again).
Before the Astro begun doing that, I don't
think I held the power button very long, just barely until the Astro vibrated (as that's the only indication I get when the internal screen doesn't work). In any case, when I rebooted from inside the updater (and the internal screen went dead) I didn't hold or press any physical buttons at all. But well, as my Astro is stock, if it tries to "multi-boot" anyway, that might be a piece to the puzzle?
As I stated above, I can now get to the recovery menu, but haven't dared doing anything there yet, except reboot and shutdown. As the screen is an OLED, it could on principle show a black image and I wouldn't know. As far as I can tell, the screen appears to be off. Once when I forced a reboot, I
think I saw a brief flash of white in a corner, but that could have been a reflection.
Both when the Astro is on and (briefly atm.) off, it shows the charge state when I have a charger connected (on the right hand side, as the HDMI dongle uses the left hand port). When I do a shut down, the LED briefly changes to red, even though I'm above 80% charge, but it soon turns green again, about when the Astro boots itself.
When I, erroneously, held power + volume down (which the Wiki says should be "Fastboot") I didn't even get a picture on the external screen, but I may have fumbled somehow, so maybe I should try that again. I have not yet tried safe mode.