Rear brake cylinder stuck extended(closed)

After 12 hours of tearing down/rebuilding my rear end I go to put my rear tire on to find my rear brake clamped shut.

Bike: 2003 yz250.

During the build i did have to smash my brake down all the way to get my rear swingarm bolt in.

All that aside now the rear brake piston seems overextended and clamped shut. I cannot seem to get it to go back in. Any suggestions, bleeding etc? I was looking for a simple solution before I drain the system to fix this.

I havn't tried more than pushing it back in and pressing the brake a few times to break it free. After working until 11pm last night on it and finnally putting the rear wheel on i was just pissed and went to bed and unfortunately im at work all day.

It appears as the cylinder is overextened. Anyone ever seen this?

thats my plan for tonight when I get home. Do you expect that to fix the issue? It was late last night and I didn't have time to try too much it just bugged me this mornign so much i thought id post to get a list of ideas to try when I get home!

successful.

Ended up being able to press it in with my fingers. I was just too frustrated and tired after 5 hours of straight work going as fast as I could. Since i had a deadline to be able to ride on Sat !

It went in easily. that is, pressing with my palms as hard as I could helped it enough. didn't know it was going to be so simple.

Now its on to fixing up my cracked or broken off drain plug!