Just received the Pi 3 in the mail. So I unplugged the Pi 2, took out the SD card from the 2 and put it in the 3. Connected everything from the Pi 2 on the 3 and attempted to boot. The image is a Ubuntu Mate and works fine in the 2, so I assumed I could just move the SD card and external USB drive over to the 3 and boot.
What I get is a rainbow color selector pattern sort of display on my screen and it doesn't go any further. Did I get a bad Pi 3 or are my assumptions about the image from my Pi 2 working in the 3 wrong?
To make sure that the sd card was still functioning I just put it back into the Pi 2 and booted. So the image still appears to work. Just strange that I don't get any text, or anything appear on the screen other than the rainbow color chooser looking screen. No text, warnings, or anything usable appears. Thanks for your feedback and help with this.