I just wanted to share what happened as it may help people in the future. I got a second AX3600, flashed it with the necessary firmware to enable ssh access and then installed initram openwrt, i then followed the instructions for the sysupgrade. It failed and I couldn't get TFTP recovery or Miwifi repair tool working, I even tried a USB to TTL adapter after opening up the router.
I eventually solved this by setting the link speed of my ethernet card to 10Mbps, after doing that and following the TFTP recovery method.
In Windows 11 > Control Panel > Network and Internet > Network Connections > Ethernet > Properties > Configure > Advanced > Speed & Duplex > Set to 10Mbps
Then follow the recovery procedure in the wiki: