On Mon, 30 Jan 2017 00:35:45 +0000 (UTC), bob prohaska
 wrote:

>Not sure this is relevant,  but I've noticed that a Pi booted without
>a monitor connected leaves the HDMI port off. Maybe your Pi didn't
>recognize the monitor in the first attempts and did on the successful one.

Not only is it relevant, it's correct!

Once I realized that my Pi was actually booting, just not enabling HDMI,
I did some online searching and some experimentation. For whatever
reason my Pi isn't recognizing my monitor upon the initial boot --
perhaps it's because the monitor is in standby; I don't know. But
whatever the reason, it appears that bootcode_delay in config.txt is the
solution. I haven't tried it, yet, but judging from the description in
the RPi documentation, bootcode_delay should do the job:
 "This is particularly useful to insert a delay before reading
  the EDID of the monitor, which can help if the Pi and monitor
  are powered from the same source but the monitor takes longer
  to start up than the Pi. Try setting this value if the display
  detection is wrong on initial boot, but is correct if you
  soft-reboot the Pi without removing power from the monitor."

Thank you.

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