I did check the servicemanual. But it didn't explain why the panel is stuck. See attached image

Service manual:

https://www.dell.com/support/home/en-us/product-support/product/latitude-14-3410-laptop/docs

I would assume that it means that the cover folds off in that direction.

As for your original post, it's possible that there's a plastic clip in the center holding the cover in place as you already pointed out. I recently worked on a laptop of another brand which also didn't mention any clips in the service manual, but with some light twisting and nudging of the cover, I was finally able to free it without breaking anything. You may want to try doing a Google or YouTube search on the disassembly of your model, as that may reveal what could be holding the cover down. Just be sure there isn't a screw that needs to be removed from underneath the keyboard.

Thanks for your reply. You are exactly right. There is some sort of catch/clip right in the middle. I tried to twist and nudged it a little but to no avail. I fear if I apply any more force, the panel might just break.

I did do a google/youtube search. The videos I reviewed just show them easily removing the panel. Only 1 video had a cut scene where it seems he too had a difficult like mine. But he didn't show how he overcome it.

I guess I can only ask Dell about it.

It looks like the arrow means to slide the panel in that direction to open it.

Same issue.

I took hold of the two tabs over the hinges and alternately lifted and twisted trying to lift up and towards the back of the laptop alternately.

The clip in the center gave way.

The clips on the bottom were hesitant to release as well, the lift and twist and pull technique persuaded bottom clips to release as well.