Send it back
...if it's truly defective.
Honestly, I find that users who are inexperienced in troubleshooting issues...may make mountains out of molehills.
New computers normally work unless there is a defect that slipped by quality control...I would get a "hands-on" look, rather than trying to talk someone into telling me what might be wrong (if possible).
I'd start with checking the connections...
If a laptop, I would probably stop there and return it. If a desktop, it's possible that some key component (video card, RAM module) became dislodged and merely needs to be reseated properly.