After the UBIFS was corrupted due to power glitch pluggy the plug computer wouldn’t boot, giving console messages
UBIFS: recovery needed Error reading superblock on volume 'ubi:rootfs'! UBIFS not mounted, use ubifs mount to mount volume first! UBIFS not mounted, use ubifs mount to mount volume first! Wrong Image Format for bootm command ERROR: can't get kernel image!
To recover the UBIFS, boot plug from USB then
$ sudo su $ mkdir /tmp/ubifs $ ubiattach /dev/ubi_ctrl -m 2 $ mount -t ubifs ubi0:rootfs /tmp/ubifs $ umount /tmp/ubifs
All being well, on mounting get messages to effect that recovery is needed, and then completed.
Lessons learnt: 1. if plug hangs while doing something, pulling the power isn’t a good recovery optiion 😉 2. It’s useful to have some alternative boot media on hand, and probably worth investing a little time to set up u-boot commands for these media.