All 4 Screws on my A159WA are frozen and I can’t unscrew them

My 10 year old a159wa needs a new battery and I’m having a VERY hard time trying to get all 4 screws loose. All 4 screws are frozen. They don’t budge at all. I used a Phillips screw driver and carefully tried to loosen them but no luck. There’s no rust or anything on the screw or on the exterior part of the back plate. It’s clean. I’ve owned this watch for around 10 years but never wore it much. It’s been sitting in my sock drawer all these years.
What can I do to get them loose? Can I use…

All 4 Screws on my A159WA are frozen and I can’t unscrew them