Canon Pixma MG5650 error B203 - How do I remove the Print Head?

After studying many answers I am pretty sure I have allowed my print head to ger blocked - in my case probably because of doing a lot of photos but not much text. In several cases the detailed descriptions of Cartridge Tray and of Print Head Set in other Pixma models do match those components in the MG5650, but the obstacles in front of them are always different: - for instance, I have read, “.. holding sides of the paper output tray, gently open it.”

Please help me to open up the MG5650 in order to get the print head out.