Chosen Solution

My speaker got hit with a ball, and now has a dent in it, the sound is not at all affected but I am concerned if this could ruin the water proofing?

From what I see you dented the metal grill over the speaker. So if you have a Boom2 unit then I think you’ll be OK (you still need to have the connectors sealed) for it to be water resistant. If on the other had have the older Boom unit then its only splash proof not waterproof!