Let's start with the dashboard, what color does the AP show in dashboard? How long has the MR been in the state of not coming up? It's possible that it was doing firmware updates. Can your customer ping the device? Have you verified the ports that the MR needs by going to the "?" in the upper right-hand corner and verifying the inbound/outbound ports are available that are needed for the MR? In your post it says all the ports are open but it doesn't hurt to double check. Worst case scenario call and speak with someone in support and they can take a look at the dashboard.
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