The screen / displays needs to be powered on before the player. If the screens are not on, the communication between the screen and player cannot happen which tells the player what resolution it can safely send to the screen. We are working on some creative solutions to this common problem. 
For now, what can you do?

3 Solutions: 

1. Turn the screen off but keep the Mini powered on.
2. Make sure the screen/display is fully powered on before the media player starts
3. Don't get on a ladder. Use remote restart in the manger app. Although the screen is black, remote restart will still work and avoid the need to power off/on.