having fixed many many tanks for customers and my own 360g, you will have to place everything in totes and provide water movement and maintain temperature.
For the tank, empty completely and wipe dry with towels.
Take a sharp razor blade (protect your fingers) and cut into corner where it leaks. Then cut away silicone pulling like a zipper. Scrape entire area clean of silicone. Then wipe clean with rubbing alcohol and allow to dry. Wipe with water and lint free cloth.
Apply a generous bead of TANK SEALANT - Not silicone . Aqueon sealant is excellent and comes in clear or Black. Apply bead into corner and smooth out evenly with wet finger or large popsicle stick. Allow to dry a FULL 36-48 hours and then fill tank with freshwater and allow to sit 24-36 hours to confirm NO LEAKS
If None, start water pumps/powerheads and add salt accordingly ( in your case 4.5 50 gal mix bags and allow to dissolve and repack your tank