Hi, I would appreciate some help.

I have two Dell U2419HC that I purchased 4 months ago. One of them stopped working - 

When I turn it on it shows a black screen with window that it is scanning for signal and that no USB Type-C is found and it goes to sleeping mode. 

- The Menu doesn't come up

- If I press button number #2 Input Source or #3 Menu, it brings up the connection selection menu

- button #4 Exit and #5 Power doing nothing

- if I press button #2 Input Source for long time it give me the option to either lock the screen of go to diagnostic mode and then only button #5 Power works - it changes colors from grey to red to green to white to black to black with wording 'Dell diagnostic test pattern'

- I have followed up on some of the other recommendations on the blog - I unplugged power cable and rest of cables pressed the power button 8-15 seconds, replugged tried different connections - USB Type-C, DP and HDMI and still, nothing works. I cant get to reset the monitor or get to the menu. 

How do you suggest I solve it?

Thank you!! Ronen