someone Passed down to me a UC520 router. I was not told of any issues with the router at all. I took the router home and at first the router will boot to ROMMON every time. I assume the IOS was either deleted or corrupted.
I attempted these methods for troubleshooting at first.: (see the link)
I understand what you are saying however if your not able to receive any information/output via the console port, I cannot think of anything else that can help. Can you try and see if there is a reset button on the UC520?