This is the eBay advertisement.
This is the screen running of a USB power cable that was included. All you have to do is plug the screen into the interface board (there is a clip that you push down to lock it in) and add power.
I flipped the screen orientation so the interface board can be eventually mounted on the back of the screen and switched to a 12 volt AC adapter. It was not noticeably brighter on the AC adapter.