Bartłomiej Piotrowski commented:
I cleaned it up shortly after the bug was opened, but there's still something wrong with hardware. Mmultiple jobs timed out on pulling Docker images and eventually it powered off completely. I have reported it to OSUOSL; runners hosted on the server are marked as paused in GitLab so won't cause problems until it's figured out.
As usually, sorry for the trouble. At some point in the future I'm going to rework runners health monitoring to use "high velocity" projects like glib, GTK and Epiphany to reliably catch such problems.