New disk still reads dead

I have two rookie questions.

I have a ReadyNAS Pro Business Edition {X-Raid2) with firmware 4.2.22 with 6 disks

Disk 4 recently died, I got a message about increasing command timeouts. An hour later the drive died.
I removed the drive with the power on and replaced it with a new WD Black 1TB drive. The system did not recognize that I had pulled the disk or inserted a new one.
I checked the HCL and it read it is not on the list. I ordered a Seagate drive from the list. Installed the new drive and it is still not recognized.

The logs do not show any activity since the failure.

I have not rebooted the device, yet.

Before I reboot I want to copy the contents to a USB drive. (we do have the entire device backed up to tape also)

My first question, I attached a 3tb that I formated with NTFS on a Windows box. It is recognized on the ReadyNAS, but it does not show a file system. Will it read a 3TB drive? I setup a backup job successfully, backing up C to the USB drive. The logs read the backup destination is a non-existent local share.

second question, Is it safe to reboot the ReadyNAS in its current condition, should I put the old dead drive back in and reboot it or reboot it with a new drive? or reboot it without the drive completely?

This is in production and I have never worked with one of these so I am a bit hesitant to start rebooting because it is not working correctly.

Thanks,