Controllerless Networks

I did the most recent firmware update on our Instant network, we have about 30 IAP 205s. 

I read that the update would change the admin account's password to be that of the AP's SN. (letters in all caps). 

I put in that combo, and it still won't let me in. I can ssh in with the old password but can't do anything with that, no configuration commands work.

Is there anyway I can switch which device is the controller so I can switch the AP that's hosting? Maybe I have the wrong SN for that specific AP, or is there another way in?

Thanks.

Update:

I removed the IAP that the instant OS was redirecting to. It went to another IAP, and same problem. The username: admin and the SERIAL (all caps) for that new one it directed to didn't work either. 

I went ahead and tried all the serials for every IAP we have, and none of them work. 

And ideas or help is greatly appreciated.

FINAL UPDATE:

After changing which IAP it redirected to as the master, I was able to get in through the CLI and change the pass. 

It didn't solve the mystery of the SN's not working, but I got back in.

The SN password on 8.5.x.x only works when the IAPs are new and unprovisioned.  If they are not new, then you should have been able to use your regular admin password.  

Gotcha. Well the admin pass didn't work after the firmware update I was unable to use the pass on the webui. The normal pass worked fine on the CLI, and then worked again on the webui after I changed it. 

So when you logged in with the original admin password, you couldn't make changes, but it let you change the admin password?  After you changed and logged in with the admin password, you could then change anything?