Wifi access point stopped working suddenly

I was in the middle of jogging my workbee (V1 with screw upgrade) and the wifi blue light went off and I lost connection. My DUET 2 has original firmware from 6 years ago and has worked flawlessly since then.

I connected my laptop with USB ( no external power on anything) and went through the wifi access point set up. Blue light is on. YAT says the wifi access point is working. On the laptop I cannot connect to the Duet. I reset passwords on wifi and tried again. Cannot connect.

Next day, I went through the whole process with wifi access point set up with same result. I tried connecting to the DUET with my phone wifi too, and it will not connect.

So, I went back and set up the DUET with connection to my home wifi. YAT says its connected to my home wifi. Blue light blinks and connects. When i try to connect with the DWC i get this message: "Your Duet rejected the HTTP request: page not found Check that the SD card is mounted and has the correct files in its /www folder"

I put the DUET SD card into a reader on my laptop and it asked me to format the disk. Which i did not do.

Now I am at the end of the road. Don´t know what to do. I would like to know what the problem likely is. Is the SD card/reader on the DUET corrupt/broken?

Because I am in the middle of a project and need to continue, I ordered a new " pre-commissioned" DUET 2 wifi from you. So ultimately this will get me going. But would be good to know what the root cause is.