Can you reseal it for waterproof protection, no. Typically, once a device is damaged or opened you lose the waterproof with the manufacturer seal. You can purchase a new adhesive that was made for that device, if available, and reseal the device yourself. Just keep in mind that it may not be completely waterproof, but the seal will help prevent liquid from coming it.
Check the model of your device, I believe this should match your model. [https://www.ebay.com/itm/Genuine-LG-V30-H930-Rear-Battery-Cover-Adhesive-MJN70408011/352242570234?epid=14012237665&hash=item52034b13fa:g:GRkAAOSwDFBaRiRv|Adhesive seal]