(Please put such output in pre-formatted CODE blocks; click </> on an empty line and paste into the new element.)
Check what happens when you follow the log:
journalctl -f
If that is too much output, reduce it by just focusing on high priority messages, like err or warning.
journalctl -f -p err
If that shows I/O Error or similar, do as @ogra suggested in the other topic.
If everything seems to checkout, you should rescue what hold dear from that device and replace it. Also, see that other link I posted in the adjacent topic:
https://cr0x.net/en/debian-read-only-filesystem-recovery/
I have since read it to the end and it’s the real deal; someone with experience showing the way to debug such an issue. Don’t bother with dmesg, though; it’s all in the journal, hence journalctl shows those kernel messages too; it can even be limited to those:
journalctl --dmesg