After a reboot I am getting boot errors

I had to reboot the server and after it came back on I got the "Failed to read blocks: 0x7" error. Naturally I suspected a dead USB as the most probable cause and promptly replaced it using a backup but to my surprise the exact same thing happened with new USB stick. I tried multiple USB 2 and 3 ports on the system to no avail.

What should I try next? Boot process is not even getting to the blue unRAID boot option screen. Straight to black screen with that failed blocks message in the bottom left corner.