Hello,
I have just bought an arduino Yun. The WiFi worked correctly and was accessible(approachable) by IDE 1.5.8 and to the address 192.168.240.1.
As you advise(recommend) it, I made the update of Open-WRT with the file Sysupgradelmage_v1.5.3.zip.
Since more access to the WiFi by the interface IDE. I tried a reset by pressing on the WiFi reset during 2 minutes but unsuccessfully. I looked for a simple solution on Web, also without succèsM.
Thank you for bringing me your help(assistant).