@askak: Yeah, that's... not good. To be perfectly honest, we could spend (some? a lot of?) time to take a dive into the logs & the system to try to figure it out, but it'd quite frankly be a lot less painful if you had a bit of Linux background.
(FWIW, that smells like a ro rootfs, which shouldn't happen during the update process (might happen with a corrupt FS, but in that case, it should have triggered a fsck at boot, which should have fixed it... :?)).
So, yeah, the full debrick/reflash might really be the easiest/fastest solution
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