SLR Film Camera Help!?

I just got this older SLR Film Camera. Its a Pentax ZX-50. I put the film in it, and after balancing the light meter, I pressed the shutter button to take a picture. The camera 'blinked' like it normally would, but it stayed shut. I thought it was just because I had a longer shutter speed, but it never opened back up. I searched around and found out that it may be because the mirror in the camera just got stuck in the 'up' position. But now, any button I press on the camera, takes a picture. I don't know if this just has something to do with the mirror problem, or there is something ELSE wrong with the camera. I've worked with these kinds of older cameras in school, so I don't believe I changed any settings to make it do this. Any help is appreciated. Thanks.