Sounds like you didn’t know what is recovery mode doing on jetons nano.
Recovery mode is a status to make the board ready to get flashed by the sdkmanager. It is triggered by the rec pin and power on signal. Pure hardware triggered. Don’t need to care about the software running on the board.
Under recovery mode, the board is totally in a brick state, which means no OS is running. I shouldn’t hear you say anything about dmesg, keyboard or anything else that is operated over the jetson nano, because there is no OS running. It is not possible to run those commands.
Please follow point 0 in below post to know how to get into recovery mode.