Trying to replace failing SD card in 994i

Trying to follow:

https://wiki.universal-devices.com/ISY-99i/ISY-26_INSTEON:Replacing/Formatting_an_SD_Card

But 5.3.4 no longer available in the referenced thread. I know it used to be. I've downloaded it myself from that very thread.

Also, no matter what SD card I put in, when I telnet in and type "FS" and answer "Y" to the prompt, it just freezes as soon as I type "Y" and stays like that forever. The only light on the front of the ISY is the power light. No other LEDS lit or blinking.

If I stick the old card back in, it boots and works but it fails with socket errors whenever I try to make any changes that result in it trying to write to the card. Prior to that, I checked the power supply (running new power supply now), network cables both for the network and PLM. I thought maybe the PLM was failing so I swapped in a brand new unused version 2.6 PLM but again get strange socket errors when trying to do a restore PLM. I get socket errors when trying to do an ISY backup (but i have a good recent backup so not a big deal on that one). The same errors happen from multiple PCs and Macs.