By gently levering with opening tools, disengage the tabs that secure the base enclosure to the laptop. Start with the longer edge. Feel free to use your hands and to lift or turn the laptop if you like.

Once you have completed the long edge, proceed along the short edges. When also these two sides will be detached, the base enclosure will come out from the bottom edge with ease.

It is very likely that tabs break down during this operation. Once you have removed the base enclosure, look for broken tabs pieces inside the laptop. If you find them, remove them straight away: they could manage to hide somewhere and cause damages in the future.