Well, I am no help as everything I can find on your pistol says the safety must be in the SAFE position in order to pull the slide all the way back and up to remove the slide.
I'm guessing you have already tried all options?
My only suggestion is: lay the pistol on its right side (I'm assuming the safety slide is on the left side). Put a drop of oil on the safety slide and set it soak in overnight. Use moderate thumb force to see if you can rock it back and forth from ON to OFF. Safeties are simple devices but when they go wrong they can be a pain.
Good Luck.
Hopefully, one of our "experts" will be along shortly.