The ‘Jacobeon method’ blocking the middle power line pin of the power brick is when the displays LED is blinking in a Short - Long - Short blink. If the displays LED is not lighting at all then you have a power brick issue.
As far as the displays USB ports power can flow from the MacBook back to the display besides from the displays power adapter via the USB connection. So that is not offering anything helpful diagnostically.
Lets get a better idea on what’s happening by installing this app [https://www.coconut-flavour.com/coconutbattery/|CoconutBattery] take a snapshot with the displays MagSafe connected to your MacBook and post it here for us to see [guide|21499]