Again my GPS was a little different. There were only 3 plastic clips holding the display. One was in the middle of the edge across from the ribbon cable and there was one on each side of the cable. the display was easily removed by simultaneously holdind the single clip back and gently pushing on the display from outside the case.
As mentioned before, this step didi not apply to my GPS.
My GPS unit, as mentioned, is soldered into the board, so no conector to remove. The GPS unit lifted right out with the board and was not attached to the display at all.
For me, there were two screws, just located at the corners. One was near where the speaker is soldered to the board and the other was diagonally across the board where the GPS unit is soldered into the board.
In my 1200, the speaker is glued to the back and soldered into the board so there is no plug to undo. Just carefully find a position so that board doesn't pull on the speaker wire while it is open.
In order to remove the rubber plugs hiding the 4 screws, I found that a straight pin angled into the top of the plug can be used to lift them easily straight out and the plug is unharmed.
With the screws out, the back did not budge. I used the thinest blade screw driver in my jeweler's set to pry the case open and pushed on the plastic catches, one on each side that were holding it closed. They are visible in the photo of the back off.