The screws were very tight in my phone. To avoid stripping the screw heads, press down with a good amount of force with the screwdriver, and twist the phone to turn the screw.

The locking tab is flat (with the top pointing away from the cable) when it is locked. Lift the tab up to unlock. It moves like a truck’s tailgate, however it’s locked while down, but unlocked when up. When you move the tab up, the cable can slide out.