I got a new baitcaster and I put some line on it. I used the line a bit and decided to replace it. So I was taking out my line and it got a knot. So I held the spool and turned the handle. After I got all the line out, the thumb button won't move. I can't press it down.

47 minutes ago, Tim Y. said:

I got a new baitcaster and I put some line on it. I used the line a bit and decided to replace it. So I was taking out my line and it got a knot. So I held the spool and turned the handle. After I got all the line out, the thumb button won't move. I can't press it down.

So with the thumb bar engaged,you put your thumb on the spool and turned the handle with thumb pressure on the spool?

Yes

 

Check to see if some of the line got wrapped around the handle. Its happenned to me before!

Im sure @Delaware Valley Tackle might have some insight.He will show up soon enough. 

The way I read the op the drag should have slipped before anything was damaged. If you want to contact me directly I'll do my best to help you figure it out.