Harddisk unknown

One of my harddisks is no longer recognized somehow.

I’ve been having problems with it from the start. In February I added 2 new HDs, bringing the total to 6. Since I only had 5 SATA power connectors on my power supply, I used a splitter, with no success. Recently I brought the server to a computer repair shop. They investigated the problem: the power supply was only 500W, which is not sufficient for 6 disks. They replaced it, so now it supports 750W and I no longer need a splitter.

Still, one of the new disks is not doing anything. FreeNAS doesn’t even recognize it as a harddisk. What should I do? Is it the factory’s fault? Or did it become corrupted due to the previous issues? Or can I just run some commands to restore it?

I probably don’t have to worry much about the data on it. It is mirrored on the other new drive anyway.