I own a ESP LTD KH-202 with a Double Locking (I think) Floyd Rose bridge.
I started changing the strings on the guitar just now, for the very first time.
I watched and read a lot of guides, but when I started with the B string, the 'string lock screw' just wouldn't twist. After some hard work, I managed to tighten the string. But when I started tuning the guitar afterwards, the string popped off from the bridge.

At this point, I can't even tighten or loosen the screw. What should I do?
Any idea why the screw was so hard to twist? Was it the thread of the screw which was malfunctioning?