OK, I’m guessing a little to some extent but if you can SSH in, try the following
Run the command systemctl stop kodi
Then navigate to the following folders and delete them
/storage/.kodi/addons/service.tvheadend42
/storage/.kodi/userdata/addon_data/service.tvheadend42
If you are using a different version of TVH then the final folder name will be a little different although pretty obvious which it is.
Then reboot.
Kodi going to safe mode is often an indication of corruption somewhere so one further suggestion is to take the upgrade tar file for CoreElec, place it in the .upgrade folder and reboot as if you are carrying out an upgrade and see if that fixes things.
And if the issue still exists.