What is the other AP(s) that you're trying to connect this IAP-277 with?
The rest of the Instant cluster are IAP-215s? The cluster is currently running 6.5.4.8?
It looks like the problem could be insufficient power to the IAP-277:
Power Status
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Item Value
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Power Supply : POE-AF
LLDP Power : 0.0W
Current Operational State : Ethernet port 1 disabled; All radios disabled;