Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.Initially, are all three (3) monitors connected to the same system/computer?
Let's go through a review of the basics:
Should all of the above check good, then it would be an internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even perhaps a soldering iron?