What you show on picture, is login sctreen not from switch (icx 7150-c12p), but from AP.
If default credentials do not work, than system is already configured and credentials are changed. So you need to get them from installer or reset configuration. Same you have to do with switch obviously.
I have 2 R510s and it is doing the same thing after I updated it the Unleashed firmware... I only managed to login twice thereafter its telling the credentials are wrong. This the second time the R510s behave this way, I'm starting to think its just bad engineering... My client is 600km away and I would have to go there and unmount the AP just to reset and reconfigure the Wireless APs... Surely Ruckus can do better with these AP firmware upgrades...
If none of the usernames/passwords work, do a factory reset on one of the access points, but disconnect the rest of the access point from the "ICX-7150", for example, if you have 3 access points, you should go to the switch and disconnect 2 of the cables to turn off the "2 access points" and only leave 1 connected with which we are going to work the factory reset.
Here is a guide how to Factory reset and configured correctly: