@SA_123: I'm sorry to hear that you have encountered this issue with the display on your daughter's Galaxy Book3 360. To ensure that the problem is not brightness-related, please try pressing Fn + F3 repeatedly to increase the brightness.
If the problem persists, please check to see if the Power LED is flashing when the device is switched on. If it isn't, then I recommend arranging for the device to be inspected and repaired by one of our authorised engineers. To do so, please head to samsung.com > Scroll to the bottom of the page > Contact us, and get in touch with our Support Team via your preferred contact method, where an advisor will be able to make the necessary arrangements for you.
@SA_123: Have you tried disconnecting the external display, and adjusting the brightness using the steps above. If so, and if the display remains blank, then a engineer's inspection is recommended to restore the Galaxy Book to it's factory specifications. I apologise for any inconvenience this may cause you.
