Liz, If new/under warranty return for exchange or refund. Err on the camera display could be the need to remove the lens and clean the contacts,make sure lens is reseated properly when you attach. See the links below for more info. on why err on Nikon display and list of error codes and what to do.
https://photographylife.com/how-to-fix-blinking-err-error-on-new-nikon-dslr-cameras
http://www.richardpeters.co.uk/blog/2011/01/07/nikon-dslr-error-codes-what-do-they-mean/
http://www.thephotoforum.com/threads/d90-error-message.263615/