R7800 OpenWrt unaccessible

I have a R7800 Netgear that I installed OpenWRT on. It functioned fine for a while but then i replaced it with a Unifi AC lite.

So it's been in the cupboard for a while. Today i wanted to set it up as a access-point for a mate that is temporarily staying at a place with dodgy wifi.

I plugged in the R7800 again and performed a hard reset using the reset button. Now i can ping fine. I was briefly able to SSH in. I know the hard reset worked because i got a warning about no password set.

However the GUI is not working at all. I have had problems with this in the past so i was planning to put back stock firmware on it. However at the moment i am not able to SSH into it either (connection refused).

I can still ping the device but nothing else seems to be working. No SSH and no GUI.

What firmware is flashed on it?

@Ansuel I can't remember. 18.x something?

https://openwrt.org/toh/netgear/r7800#debricking should always work.