Like Terry said, the shutter will stay open based on three things...
- Amount of light you are aiming at
- ISO setting (3000/75 ISO aka Black and White/Color)
- Brightness selector setting
There should be 2 clicks. First is that shutter cock lever popping back up as soon as you push the shutter button. Even if there are no batteries, or they are dead, you should get the first click regardless.
Second click should be anywhere from moments later to a while later depending on the above. What I would do is aim the camera at a bright light source, make sure it's set to 3000 (no film in it) and set the brightness adjustment to the standard setting. Then cock the shutter and fire, holding until the 2nd click is heard. Make a note of the time it took. Then, aim the camera somewhat away from the light and repeat the process. The shutter length should increase depending on the change in the light.
Also, make sure to hold the shutter down until you hear that second click, even if it takes a while. If you never hear it, it's the batteries or insides that aren't working. if it just takes a while, it's an exposure issue most likely.
You can also open the back and look through the opening to see the shutter open and close and try both ISO settings to see if they make any difference to narrow down the issue.