Can't get the four screws removed to even start to replace the battery

I used a tri wing 1.5.

Rest will not do the job.

make sure the correct bit is definitely in use. Samsung use a special kind of glue made specifically for screws to prevent them working loose with vibrations called thread locker. You need to apply enough pressure for the tri-wing bit to not "cam out" of the screw head. If it "cams out" then it can damage the screw.

Pressure and making sure the correct bit is in use by checking if it catches the screw by turning the screwdriver gently with little pressure and letting it fall into the screw, you will feel it catch and not want to turn. you'll feel it trying to catch it and not quite doing so if you are using too pointed a bit and you will feel it begin to strip if you use too small of a bit. You shouldn't need to replace the thread locker once you have finished your repair.

watches that have never been opened before can sometimes be quite stubborn