Sonicwall only boots to safe mode

I recently got my hands on a used TZ 170 firewall, and thought I could use it for "training" purposes in order to be able to better configure similar devices for customers, but I am not able to get the device to boot into "normal" mode, even after at least attempting to put it back to factory defaults.

It will only boot into safe mode, and only does this when I press the "reset" button on the back and hold it in while I plug in the power adapter, then release the button. I can get to the default homepage (192.168.168.168) only if I hard-code an IP address on the same subnet to my laptop. I cannot get a DHCP assigned address in safe more, or in normal mode.

I thought the firmware was corrupted, so I downloaded the most recent copy from the Sonicwall website, and I am able to upload it to the device, and it gives me 3 firmware versions to boot from - normal, normal with factory defaults, or normal with "backup" configuration. I've tried all three options, but as soon as it attempts to boot from any of them, it hangs, and I have to manually reboot it.

At this point, it will give out standard 169.254.x.x IP addresses instead of something in the 192.168.168.x range. I've searched online everywhere I can think of but I'm not finding any useful information.

Any suggestions, besides tossing it?