The Debian package 'xserver-xorg-video-intel' is missing from the full 64 bit 2018-12 GRML disto.
If your device has an Intel graphics card and you can't boot to X then installing the missing package will fix the problem:
$ apt-get update $ apt-get install xserver-xorg-video-intel
The 64 bit & 32 small distros are also both missing Intel drivers, however restoring the package will incur an additional 240 MB of dependencies asscociatted with it.
Listing this as a known bug on the GRML web site would have been very helpful.
Strangely I recently had a similar problem with another Debian Linux distro uprgrade, perhaps this is a Debian issue rather than a GRML bug.
Anyways, now everything is sweet.
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