I'm trying to get the Pi 3 to work with the official screen for the past couple of hours without any luck.
I've started with installing a fresh copy of Raspbian and did update & upgrade over HDMI. Enabled SPI & I2C in raspi-config, disabled overscan, added more GPU memory and even tried rpi-update. Tried the official troubleshooting steps, but I kept getting stuck at a rainbow screen. Tried powering the Pi 3 and the display separately - same result. If I boot with the HDMI cable in - it boots, if it's disconnected but connected to the DSI - rainbow screen. No DSI (headless) - boots fine. The screen works fine on a Pi 2. Wat is dis sorcery?