The attached photo is a hard disk control board (part no '4952 K') from a failed Seagate Barracuda 8TB drive (ST8000DM0004).
A simple test with a multimeter suggests that what appears to be a transistor has failed.
There is an open circuit across two of the pads. i.e. the middle pad at the top (collector?) and the left hand pad at the bottom (base?).
It may be a bipolar transistor or a FET of some sort.
The device is outlined in red in the photo.
The number marked on the device looks like 'TR1' followed by either a strange looking '7' or a 'J' rotated by 90 degrees.
Can anyone help identify the device?
I am hoping to replace it and repair the drive.

I have discovered you can buy complete replacement PCBs (Part No: 100784953) from places like Aliexpress BUT apparently the BIOS chip has to be swapped over so that it matches the rest of the drive. It is a multipin SMD device. Swapping it is beyond my capabilities - I don't have the tools or the skill.

After a lot of searching around, I suspect the device is an N-Channel Power Mosfet NTR4501N.
In that case the top center pad is the drain and the lower left pad is the gate.
Hence my thought that the device was faulty is probably incorrect and I will be unable to repair the drive.

 

Possibly NTR4501N.

https://www.onsemi.com/download/data-sheet/pdf/ntr4501n-d.pdf

 

The component you marked ("TR17") is indeed in a typical footprint for a power MOSFET in a SOT-223 / DPAK-like package. The labeling on HDD PCBs can be confusing because “TR” sometimes refers to a transistor (general), but in HDD power rails it’s usually a MOSFET used for 12 V or 5 V input protection. Current limiting / switching.Transient suppression in conjunction with TVS diodes.