These plastic clips are very popularly used, must be very careful to use force.

when you hear the "snapping sounds", you probably already broke the clips.

About "Note that there are screw covers on the sides (two on the left and one on the right).":

1. Are these screw covers glued?

2. After finish replacing any parts, do I need apply glue to attach these screw covers again(or they are self-glued)?

3. Is this method(screw covers cluing) very popularly used with IBM Thinkpads?

(I need to replace Thinkpad X40 LCD rear cover, but not confident to start)