I was hoping maybe the updater could catch it before it reboots. But if it doesn't even see the network, it won't work.
You can wait and see if any of the linux ppl here have some ideas to get the unit into EM mode, if that is even possible in its current state.
Hopefully your data is already backed up.
With the firmware being shot, I don't know what else can be done besides wipe the drives and start over.
And that's going to require firmware boot file extraction:
Plus, the use of TFTP to load the boot files: (I have a TFTP boot and firmware file set for the TS-XEL, PM me if you want it)
Or without TFTP with the steps in this article:
https://buffalonas.miraheze.org/wiki/Restoring_Stock_Firmware_without_TFTPAfter it boots to EM mode, you'd run the manual install of the 1.73 firmware.