Torx screws T10 or T15 I think. Might need a torx bit set and some right angle 1/4" drive tools. Whole pile of screws including 2 in each defroster vent (don't drop them) and all.
Takes about 5 minutes to get it out of there. Screws strip easily in the plastic upon reinstall too so be careful.
Better glue it slightly bent the way it looks cracked or it most likely will crack again. They don't like to be confined on the ends with the speaker screws when they are perfectly flat. If I had a new good one I wouldn't even use the screws in the ends.