Please follow the directions here to manually upgrade to 6.12.1:
https://docs.unraid.net/unraid-os/manual/upgrade-instructions/#manual-upgrade-or-downgrade
If you continue to have trouble after the upgrade, from telnet, SSH, or a local keyboard/monitor, sign in and type "diagnostics", it will put the file in the "logs" directory on the flash drive. You can then upload those to a new thread in general support where you describe the issue. It is very difficult to troubleshoot in the release thread, so a new thread is best.