Here's the problem. I can flash a new image using Noobs and with the same powersupply I can boot in graphical mode without problem. When I flash an image for work, I only see a black screen with the multicolor square flashing up on the top right corner of the hdmi display or rca display.
The device is initially configured to run with a LCD Display but as I see the square on any other display that I connect, I have the feeling that video output is actually detected (could be the gpu broadcasting on any interface).
The thing is that during the boot phase, I don't see anything either. Usually we would see the pi logo with some boot logs but with that image it's completely black.
I have the feeling like the PI is trying to output to a the LCD that isn't connected... Any idea how to disable the video port and force hdmi?
Writing "hdmi_force_hotplug=1" in boot/config.txt doesn't seems to help.