Since the methods you tried didn't work, the next step would be to remove the head unit and send it out for repair. You can send it to Bose Corp. for repair or an independent company that repairs Nissan Bose head units.
For Bose Corp., you can email them at [email protected]
or call customer service at 1-800-379-2073.
For independent companies, do a web search for "Nissan Bose radio repair."