If you have Master AP already installed then the upgrade is one of the easiest thing to do in Unleashed. After you logged in as ‘admin’ go to ‘Admin & Services - > Administer -> Upgrade’. On the right hand side you will see ‘Current firmware version’. If it is already running 22.214.171.124.228 then the Master AP is already running the latest image and no need to do any upgrade. If it is running some other version then all you have to do is to select 200.3 (default) and click ‘Upgrade’ button. This will operation will upgrade both the Master and Member APs automatically.
If Unleashed AP’s ‘Power LED’ (regardless of whether it is Master or Member) is flashing then it means that the AP did not receive any routeable IP – likely a DHCP or network issue.
In Unleashed 200.2 the resiliency of Unleashed has gotten a lot stronger. In other words, every Ethernet connected AP in Unleashed network is a potential ‘Standby’. If Master were to go down then one of the Ethernet connected APs will become new Master. This phenomenon will continue till the last AP with Ethernet connection stays alive. So, it is more dynamic resiliency and no need of any user intervention. An Unleashed network could have up to 25 Ethernet attached APs, out of which 24 are Standby-Masters and it would look very awkward in the UI if every AP shows as 'Standby-Master'. Hence, it is not displaying ‘Standby-Master’. But now you know the behavior.
When you unplugged the AP1 (Master) did AP2 become a new Master? If so, the clients should be connecting to the new Master. If this isn’t happening then open a Support case to troubleshoot the issue.