So first off to confirm the hdd itself is ok, works on PC and solo2.

My first observation that the solo2 mounting system is well thought out, no contact between bracket and hdd pcb, and rubber mounting spacers. Whilst on the h7s there is no rubber spacers, and the screws dont go all the way in so its a loose fit, the bracket can touch the hdd pcb. I didnt power it up in this way, I used the rubber spaces from my solo2 so it was snug stable installation and with no contact with pcb.

After hdd is installed with power and data cables connected, it simply isnt detected in the OS. Either in cli or the gui.

Does this suggest a faulty box?

Putting my ear to box I dont think the hdd is even powering up.