Ok after one more disassemble-reassemble of the AirPort Extreme, everything works fine now. I don’t know what was the problem, maybe it could have been the fan connector which I didn’t properly put back in place the first time I did the job.

Great thing I didn’t have to replace the fan, cause it would have taken about 50 days for the spare part to ship from China!

I am gonna order a couple of those fans anyway, it looks like this could be the weak part of this great router

Mine was having its fan being too noisy. After having followed this guide to get to it, I’ve managed to clean it up and put some lube on its pin.

I’ve reassembled everything back in place, but now I get the infamous message “this device may be overheating”. It seems that the fan doesn’t spin anymore. Any clue about what can cause it?