It sounds like either a filter is clogged, an air vent in the back is blocked, or the internal cooling fan is not running.We have a sound clip here of what a microwave should sound like when the cooling fan and high voltage section are working.
This overheating can happen if you put it in a cabinet or push it against a wall.Many Emerson microwave
owner's manuals are available for free download here.
yours may not be there, there might be one close enough to help you.
For more help from
here or get
help using your appliance at 1-800-898-9020.
Since it's new, it's under warranty, and any trouble you have should be taken care of.
Get help locating an
authorized servicer or parts at 1-800-695-0098.
happy to help you with free advice and we'd appreciate your
thoughtful rating of our answer.