When you say stop power do you mean you want to disable the power to the drive (child lock out, stop the annoying spin noise when you have a disc in, power reduction... it really does not matter) or that your drive is broken and you heard some three legged chip (don't know if that is a transistor, regulator or something else entirely offhand) might be the cause?
If you are asking this sort of thing for the first scenario you are probably also kitted out to figure it out yourself. I would probably start at the drive end, look at whatever cables are coming in and then figure out what it uses to power things beyond that (it should be fairly obvious what is signals and what is local power smoothing/correcting/voltage twiddling).
For the second scenario I would probably do something similar but work back to those chips. Thermal vision is fun, as is having something working to compare to, but you can do just as well by putting some alcohol on them (if you are at all considering fiddling with these sorts of things you or someone you know should have some IPA/isopropyl alcohol for cleaning things) and seeing what evaporates (if it is failed short then it should heat up massively and evaporate quickly, if one is failed open then it should not heat up and instead the others will evaporate leaving that behind for a while).
I have not seen discussions of PS4 circuits get to this level, nor diagrams made available (assuming one can identify what board that is and what revision it is -- I don't know what ones are out there but there are bound to be several).