I have a Seagate 1 TB SSHD that recently stopped working. I was able to read it via a Linux Live CD but it was unable to boot into Windows and the Win7repair funciton would not work. I was tryingto recover the boot mgr/ MFS table with Testdisk and now it appears as a Block Device and reads empty. I did a dmesg | grep/dev/sda and received the output below:

root@kali:/dev# dmesg | grep sda
[ 323.087309] sd 0:0:0:0: [sda] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
[ 323.087315] sd 0:0:0:0: [sda] 4096-byte physical blocks
[ 323.087339] sd 0:0:0:0: [sda] Write Protect is off
[ 323.087342] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[ 323.087353] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 328.729636] sd 0:0:0:0: [sda] tag#24 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.729644] sd 0:0:0:0: [sda] tag#24 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.729648] blk_update_request: I/O error, dev sda, sector 0
[ 328.729653] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.729815] sd 0:0:0:0: [sda] tag#25 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.729824] sd 0:0:0:0: [sda] tag#25 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.729828] blk_update_request: I/O error, dev sda, sector 0
[ 328.729832] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.729891] sd 0:0:0:0: [sda] tag#26 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.729897] sd 0:0:0:0: [sda] tag#26 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.729900] blk_update_request: I/O error, dev sda, sector 0
[ 328.729903] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.729964] sd 0:0:0:0: [sda] tag#27 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.729971] sd 0:0:0:0: [sda] tag#27 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.729974] blk_update_request: I/O error, dev sda, sector 0
[ 328.729977] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730053] sd 0:0:0:0: [sda] tag#28 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730060] sd 0:0:0:0: [sda] tag#28 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730063] blk_update_request: I/O error, dev sda, sector 0
[ 328.730066] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730132] sd 0:0:0:0: [sda] tag#29 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730138] sd 0:0:0:0: [sda] tag#29 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730141] blk_update_request: I/O error, dev sda, sector 0
[ 328.730145] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730206] sd 0:0:0:0: [sda] tag#30 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730212] sd 0:0:0:0: [sda] tag#30 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730215] blk_update_request: I/O error, dev sda, sector 0
[ 328.730218] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730280] sd 0:0:0:0: [sda] tag#0 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730286] sd 0:0:0:0: [sda] tag#0 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730289] blk_update_request: I/O error, dev sda, sector 0
[ 328.730292] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730331] Dev sda: unable to read RDB block 0
[ 328.730358] sd 0:0:0:0: [sda] tag#1 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730364] sd 0:0:0:0: [sda] tag#1 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730367] blk_update_request: I/O error, dev sda, sector 0
[ 328.730370] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730539] sd 0:0:0:0: [sda] tag#2 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730542] sd 0:0:0:0: [sda] tag#2 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[ 328.730543] blk_update_request: I/O error, dev sda, sector 0
[ 328.730544] Buffer I/O error on dev sda, logical block 0, async page read
[ 328.730586] sda: unable to read partition table
[ 328.730754] sd 0:0:0:0: [sda] Read Capacity(16) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730759] sd 0:0:0:0: [sda] Sense not available.
[ 328.730789] sd 0:0:0:0: [sda] Read Capacity(10) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 328.730792] sd 0:0:0:0: [sda] Sense not available.
[ 328.730833] sd 0:0:0:0: [sda] Attached SCSI disk
[ 435.077584] sd 0:0:0:0: [sda] Read Capacity(16) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 435.077592] sd 0:0:0:0: [sda] Sense not available.
[ 435.077650] sd 0:0:0:0: [sda] Read Capacity(10) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 435.077655] sd 0:0:0:0: [sda] Sense not available.
[ 448.222134] sd 0:0:0:0: [sda] Stopping disk
[ 448.222189] sd 0:0:0:0: [sda] Start/Stop Unit failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 449.392856] sd 0:0:0:0: [sda] Starting disk
[ 449.735686] sd 0:0:0:0: [sda] Start/Stop Unit failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 575.141805] sd 0:0:0:0: [sda] Stopping disk
[ 575.141855] sd 0:0:0:0: [sda] Start/Stop Unit failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 576.301454] sd 0:0:0:0: [sda] Starting disk
[ 576.618964] sd 0:0:0:0: [sda] Start/Stop Unit failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 7023.192588] sd 0:0:0:0: [sda] Read Capacity(16) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 7023.192596] sd 0:0:0:0: [sda] Sense not available.
[ 7023.192663] sd 0:0:0:0: [sda] Read Capacity(10) failed: Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK
[ 7023.192667] sd 0:0:0:0: [sda] Sense not available.


There isn't any critical data that resided on the drive but it would be nice to be able to put it back into use even if I can't recover the data.

Any suggestions?

Welcome aboard.

I think that says it all, no partition table.
As there is no critical data on it, just put it down to experience.
Just repartition it, put a filesystem on it, & use it.

What is the output of "smartctl -a /dev/sda" as root?

With all of those I/O errors you probably have a ton of reallocated sectors, and you finally lost a sector related to the partitioning setup. Even if you repartition it that drive is most likely on its last legs and will give out very soon.