Cannot mount drive after reboot

[peter-s-c]

I'm running a D5-300 on Mac OS 15.1.1 connected to a Mac Studio.

On my most recent reboot, the disk will not mount. When running Raid Manager Pro I get the following error message:

The connection between APP and RAID HBA has been interruptted, APP will try to reconnect RAID HBA in 2 second(s).

On running Disk Utility I get:

Running First Aid on “Terra Master Video Data” (disk5s1)

Checking file system and repairing if necessary and if possible.
Volume is already unmounted.
Performing fsck_apfs -y -x /dev/rdisk5s1
Checking the container superblock.
Checking the checkpoint with transaction ID 545516.
Checking the space manager.
warning: (oid 0x10150) cib: invalid o_cksum (0xffffffffffffffff)
error: failed to read spaceman cib 76 at address 0x10150
Space manager is invalid.
The volume /dev/rdisk5s1 with UUID 00000000-0000-0000-0000-000000000000 could not be verified completely.
File system check exit code is 8.
Restoring the original state found as unmounted.
File system verify or repair failed. : (-69845)

Operation failed…

Is it dead or is there a solution?