...And we're back to this issue, at least on my A20Lime (not Lime2, in case it matters) archive server: linux-u-boot-lime-next_5.60_armhf.deb won't boot without HDMI active. Fortunately, /var/cache/apt/archives/ still contains linux-u-boot-lime-next_5.38_armhf.deb. which does.
dpkg -i /var/cache/apt/archives/linux-u-boot-lime-next_5.38_armhf.deb
Thanks for your efforts, folks. I'm loving how dead-simple-reliable this Olimex board (5 watts w/ HD!) and Armbian are.