Hello!
I really dont know if there is a way to change to mode manually via cli...or GUI ... at least i have not read it...
What i have done to convert it back to the standard IAP mode is what i said before...
So jRemenber this is an assumption... i really don tknow if its on stand alone... but it could be IF he is on the same vlan as the other APS and he is on a VC by its own... if its like that then its most likely on stand alone mode...
BUT if that VC got at least 2 APS then, its not in stand alone and its something else...
So in summary:
connect to console to the IAP which is alone on his VC, reset that AP and go in the bootap mode, on the bootap mode do:
clear os
purgeenv
saveenv
reset
And then take that ap which should be on factory default now, and plug it in the network again...
He will get the config and the firmware from the other Instants APs.
Cheers
Carlos