Also: please check the other end of the cable, the one that isn't plug in the wall, yes that one, plugged on the screen, unplug and plug it back in please.
I appreciate HW engineers and techs. I'm not afraid of datasheets, circuit diagrams, or a mso and they're always patient enough to explain things to me so I can make the rocks behave. Or at least tell me how to go from diagram to board lol.
At a former job, there was one -- and only one -- lady in customer service who would actually reboot and do all the basic troubleshooting steps before calling IT. If we heard from her, we knew something was legitimately broken. Oddly enough, I'm married to her now. Best decision I ever made.
Did pretty much the same with a new server recently - spent ages debugging why it didn't find the SAS disks. Turns out, disks like to have power connected, and no amount of debugging on software level will help you.
Always turn it off and on again. Then check cable and physical connections, then start the real troubleshooting. I have fixed over a thousand computers as a hobby. So I'm no pro, but I know that much.
I spent what felt like an eternity debugging a website because it wasn't updating. You gussed it, I was looking the build output of webpak in the wrong folder.