Unable to access DS920+

I recently tried to update my 920+ to 7.3 from 7.2.

During the update, the countdown froze at 17:30, and I left it for around more 30 minutes before refreshing the window. Around an hour later, when I looked at the NAS, it had a flashing blue power button and was completely unresponsive to power inputs, so I had to hold the power button down until it forcefully turned off. It did come back with a solid blue light, and all future power offs and ons have resluted in a solid blue light.

I've tried both a mode 1 and mode 2 reset.

find.synology.com is showing one of the old static IPs I used to have assigned that I could not access the device on before or after the update.

Synology Assistant is giving a more reliable picture, showing the device is connected through DHCP, has a valid IP (that I can ping and get a response from) yet I cannot connect to DSM.

Despite doing a mode 2 reset, and hearing the first beep from the network reset, and then the three beeps to confirm that mode 2 was completed, Synology Assistant still marks the device as "Ready" with no configuration lost/reinstall needed.

After doing a mode 1 reset, the device was detected with a local link address, and if I tried to reset the network settings, it told me the admin password was incorrect. Username admin, with no password.

I'm at a loss on what to do. The hardware seems fine, just DSM is broken.