Sergi,
Can you also run a "capwap ping <server IP>"? This will send ICMP over the CAPWAP port. This should succeed. I say that only because it was connected prior to you updating the AP in some form.
It's odd that a firmware update is also impacting its connection. I'd expect the config update to possibly cause this if something was improperly configured and being pushed to the AP (native VLAN, or mgt0 VLAN change).
Also intriguing that a simple reboot of the AP breaks the connection.
When you ran Sams above commands, did they all work? I traditionally use "capwap client server name <HM IP or name> vs. "hivemanager <hivemanager address> primary". It looks like "hiveManager <server> primary" does indeed work as does "hiveManager vhm-name <vhm name>"! Learned something new from this thread.