Hemos probado en otra tv y lo mismo, alguna solución???

Graciass
Vamos, que uses el theme "Carbon" para confirmar el bug, y si es así, usar las opciones 1 ó 2White Screen of Death
There is a fundamental bug with EmulationStation where unique background images are not loaded dynamically so if you have more than ~10 systems (on most themes that have a unique wallpaper per system) you will start to get a white screen of death and nothing will show up.
There are a few things you can do to fix the white screen of death:If you can't access the theme changer in emulationstation because it's a white screen, you can ssh into the pi and change the theme name back to carbon in the backend in /opt/retropie/configs/all/emulationstation/es_settings.cfg
- increase your GPU/CPU split (see here)
- remove some systems
- switch your theme to any Carbon, Pixel, Eudora, Turtle-Pi, or Canela variant (as they have one static background and therefore don't crash when you have many systems)