This occured during an upgrade at a remote site from 3.3 to 3.4. After the IAPs rebooted after the upgrade
I could not log into them with the configured uid/pass nor with the default uid/pass. Also they were no longer
transmitting out the configured SSIDs of the default "instant" SSID.
I had a on-site novice use the reset button procedure to default one IAP but this did not clear the problem.
Once both IAPs were shipped back to us, I tried the reset button procedure and connecting via serial console connection
and performing purgeenv and clear os but it still no access.
We have an RMA in process to replace the units but is this a known problem during upgrades and is there a backout procedure
if this happens again? I have 20+ international remote sites with IAPs with no technical level help at those sites.
Should I power down all but one IAP and perform the upgrade? If it completes correctly bring up the others to sync to the upgraded leader? And if it fails power down the failed IAP and and bring up the others?