Kyle, I'm assuming you don't have a crystal or caseback press? If simply applying pressure with your thumbs doesn't close the case, try flipping in around and pressing down with more force. Important, do NOT apply pressure to the glass as you risk chipping, cracking, or damaging the gasket. You'll want to find something hard with a hole slightly bigger than the glass and put the watch face down in it. Then you can apply more force without risking the glass or water resistance. The easiest and best solution is to take it to a watchmaker to close as it should be waterproof tested as well.