This is the culprit that almost made me toss my old Vizio in the garbage...
Yesterday when I thought the HDMI board went tits up, it was the GD USB ports that were not powering the Amazon Firestick. I learned this while getting the same problem on the new TCL display. I tested the Firestick on the bedroom setup 3 and it worked. Then I brought the ROKU from setup 3 back to setup 2 and teh TCL did not detect any input activity on its HDMI ports from the Roku. I tried all 4. Then I thought about using a power cube to power up the ROKU and voila, I got a display show up on the TCL. I then ran the same test on the Vizio and I saw the ROKU menu show up on the Vizio. It never dawned on me that the USB ports would go bad.
Needless to say, the TCL is going back even though its a much better display than the Vizio. I had to jump through hoops to get Amazon to arrange a pickup as they wanted me to ship it back on my dime.