How do I remove the bottom?

I just want to clean up the inside of my MacBook Pro 15” A1990 that I have had for 2.5 years, but after unscrewing the 6 screws and undoing the internal clips, I can’t get the bottom to slide off.

I have seen numerous guides and they all show the same thing: After undoing the clips, they slide the bottom down from the hinge and it comes off easy. But when I try sliding down, it doesn’t budge even slightly.

It may be worth noting that the Apple Genius Bar has done a repair on this MacBook in the past.