Cannot Mount an External Drive

Took the external drive to a friends Apple laptop yesterday. Downloaded some files. Now it won't recognise itself on my every day iMac in the studio.

Have tried running Disk Utility.

(here are the results from running the programme)

Running First Aid on “Scarlet TwoTerraDrive” (disk4s1)

Repairing file system.

Volume is already unmounted.

Performing fsck_apfs -y -x /dev/rdisk4s1

Checking the container superblock.

warning: container has been mounted by APFS version 1934.141.2, which is newer than 1677.141.3.7.2

warning: disabling overallocation repairs by default; use -o to override

Checking the EFI jumpstart record.

Checking the space manager.

Checking the space manager free queue trees.

Checking the object map.

Checking volume.

Checking the APFS volume superblock.

Checking the object map.

error: (oid 0x23229f) om: btn: invalid o_oid (0x3be7c)

error: (oid 0x23229f) om: btn: invalid o_subtype (0xe, expected 0xb)

error: (oid 0x23229f) om: btn: invalid o_type (0x3, expected 0x40000003)

Object map is invalid.

The volume /dev/rdisk4s1 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…