Oliver Wilson wrote:

My main confusion about the SATA 0 unknown is whether it's the 1TB disk
that's bad, or the RAID card that is bad.

I think the message about SATA port0 is referring to a SATA port on the
motherboard, not a SATA port on the RAID card.

I seem to see you saying that you think the 1TB drive is actually good?
Did I understand that correctly?

One of your photos shows the RAID card saying that all four drives and
all three arrays are good.

If the 1TB drive is likely good, then are you saying the RAID card is
likely bad?

Hopefully it is good too, after all one of your photos does show the
RAID card having detected the drives and saying the arrays are optimal.

I would move the card back to the slot it was in, different PCIe slots
can have different numbers of "lanes" and the PCIe training error you
show is referring to the motherboard and PCIe card being unable to agree
the correct number of lanes to use.