If you can access the console, you can upgrade the image over TFTP as well; however the console has a special 4-pin header and you need a level converter cable (AP-CBL-SER) TTL-RS232 to connect it to a serial port.
If you can SSH into the Instant AP, you can use the upgrade os commands there as well to upgrade either flash partition:
d8:c7:c8:cc:45:54# upgrade-image?
upgrade-image
upgrade-image2
upgrade-image2-no-reboot
d8:c7:c8:cc:45:54# upgrade-image ?
<url> ftp/tftp/http URL syntax
From the WebUI you only see the current running version, and by upgrading twice (the upgrade will put the running firmware in the backup slot), you can make both slots the same firmware.
I have never seen an Instant AP with the automatic update procedure switch into a campus AP; however again the 3.0 firmware is pretty ancient and upgrading manually with firmwares that you download from the support website will most times do the thing...