I'm not sure if you've been able to test the exposure meter but if you are to test it (I own a colorpack2 and a squareshooter) the method I use is to go into a bedroom or somewhere in your home, turn the little 'light/dark' dial to anything (preferably a setting youd use normally) and press and hold the shutter while aiming the camera down toward the floor, the shutter should stay open, when you bring the camera up toward a light, or a brightly lit wall you should hear the shutter click closed. (the shutters on these cameras SEEM like they are working when the battery isnt in it, but they really arent, the batteries power the light meter, which controls the shutter..... the mechanism that triggers the shutter clicks and make noise without the battery in it but light never hits the film due to the shutter being open)
Attempt this at different 'light / dark' settings to see if this affects anything. If the dial doesnt alter the sensitivity of the meter or the shutter makes a clicking noise but doesnt actually open, you might need to look for a new camera, or as already suggested try one of the faster films and find out the quirk and what you need to do to get around it. You might need to clean the little 'eye' of the exposure meter also.
I've had similar problems, in the past, with my squareshooter and my colorpack2 both either completely overexposing or not exposing at all. Ive never been able to fully discover why this happens, it seems to be just really poor shutter/meter combinations. Out of a 20 pack it usually happens to 2-3 photos but not all of them.....
If you are close to any thrift shop of any sort, Salvation Army, Goodwill, in the USA etc, these usually have at least one polaroid from the late 60s, early 70s era, usually for $2 or $5 (at least in my town I've seen them a lot!). I would recomend having a look at some shops like this if you can find one a colorpack2 is a great thing to play with, a glass lens, selection of ISO speed and a larger format...the film seems to be easier to get as well..
some questions, has it worked at all?
have you tried letting it develop for say, 10-15 seconds then peeling it apart to see if there is ANY image? I might try this!
hope this helps in some way
edit: also, its safe to completely remove the film holder pack after you already removed the 'darkslide' but you WILL lose 1 frame, but thats it. so if you needed to change batteries, or look inside to see whats going on, the most youll lose is that 1 picture...