Replacing window blind

I have replaced a number of blinds on my camper but am struggling to replace the one immediately behind the driver. I have got so far but struggling to release the bottom of the screen from the vehicle. There does not seem an obvious way to do this. Can anyone help?

I removed the top curtain cover strip 280mm long (6 screws) then curtain rail to undo top frame screws, remove bottom piece that has rear cushion snaps fitted 120mm long, remove 3 side panels (1 short above left side of sink unit) screws hold curtain straps. I then removed long screws that hold complete frame to van body 3 bottom 1or2 each side. the main frame then came out, and I was able to repair blind with frame laid on a table.