Turning the takedown lever compresses the recoil spring. On new guns, these springs are mad stiff! I had the same issue with my Shield 1.0 when new and several other pistols. I had a hard time even racking the slide to get it to slide lock.

It will ease up with use. I suggest rather than a screwdriver, to wear a glove or pad the takedown with a rag or paper towel. Make it respect your authoritah!!

The sear deactivation lever should return when you insert a mag. Once you get the slide off, try inserting an empty mag.