run Dell Diagnostics  Just know you don't have much time to return for a full refund or you are stuck with the laptop.
The screen of my 7-day-old Latitude 3420 jittered when I touched the "Exit Full Screen" mode on a live on-line video I was watching (Not ZOOM, YouTube, Crowdcast or FaceBook )- this NEVER occurred with my MacBook with the same video source.  I do not want to go into time-consuming set-up changes or download but would like to know whether this is a sign that there is a problem with the laptop. Thanks for any help.
Jittering screen