Ok, something weird going on with my hardware, after booting from power off 3 times, the screen suddenly came up again on Ubuntu.
My ext3 filesystem Arch install became corrupted (The SD card is not recognised by any machine), so I am back to rebuilding the card .. I will do it in ext2 format this time, and see if it is more stable.
By The way, when I do a pacman -Syu in a chroot environment, when it gets to the point of installing the files, I see lot's of these style errors:
$this->bbcode_second_pass_code('', '(14/50) upgrading libgcrypt [################################] 100%
/tmp/alpm_5H03p9/.INSTALL: line 7: /dev/null: Permission denied
/tmp/alpm_5H03p9/.INSTALL: line 7: /dev/null: Permission denied
error: command failed to execute correctly')
Does anyone know if this is benign?