I've just tried this exact set of parameters in /boot/config.txt on a clean Jessie Lite image, with both HDMI and touchscreen attached, it works.
The obvious would be that the DSI cable was not secured properly and came loose.
I've just tried this exact set of parameters in /boot/config.txt on a clean Jessie Lite image, with both HDMI and touchscreen attached, it works.
The obvious would be that the DSI cable was not secured properly and came loose.