That doesn’t look good! What happened and how did the leak occur? @mau792 is correct, its definitely possible that there may have been some debris on on the o-ring groove that could have comprised the seal. Was it saltwater or freshwater that got inside?
Unfortunately, there isn’t much that can be done for the battery now. Water shouldn’t immediately cause a short, but it will make the battery corrode quite severely internally. We have gotten batteries wet in our testing before, and they have corroded significantly- we discontinued use and threw them out when we noticed what had happened. My recommendation would be for you to do this as well is the battery was completely doused. If just the connectors got wet and the rest of the battery is fine, you can just cut off and replace them.