.. Small screwdriver

It is. Well, I guess you need a smaller screwdriver.

There is another option, too.

Make your current screwdriver smaller.

Wouldn't it be cool to possess magic to do just that?

Some magical item that can make stuff smaller. Maybe you have encountered one, already?

In the lobby. Use the stuff on the tables. ( Use the cursed flowers. )

The cursed flowers will make stuff smaller. Use the flat-head screwdriver on the flower to make it smaller. You can now unscrew the mini screws.