To BillM who posted in June 2011 -- thank you!
Quote: If viewfinder does not darken and no noise is heard,power down and remove lens.
looking inside,on left side of opening,about center verticle you'll see small square fitting
that sits on top of a verticle slot or track.When found,power up and
very gently bump square fitting with finger tip in both directions (up/dow
n).
Here's my story...
I got a Pentax ZX-M on eBay. It came with a near-dead battery. I was able to fire off some shots without film, I thought wow I got a great deal on a lightweight SLR. Then on the next shot the mirror locked in up position. I thought needs a new battery, but didn't have any CR2 batteries and so I ordered a 12-pack from Amazon. Meanwhile, thinking I could test it without proper batteries, I took the camera base off and poked around. I hooked up 4 AAs and then tried a spare 6VDC a/c adapter.
None of that worked at all -- total waste of time, except for the "learning experience" !!
Batteries came today. I was not hopeful. But I popped two into the ZX-M and the camera came alive! Wow! Shutter fired, what a difference! BUT, then I loaded some 2002-expired film (which an eBay seller had included in another camera deal) and just like what happened to the OP saab_princess_21, it went to "1" and then rewinded the film! What the what?! I got the film leader out, cut the end and made a new leader. Loaded and it rewinded again!
That's when I found BillM's suggestions -- that little bit of info about the diaphragm actuator on the camera body was the key to solving the problem. I gently pushed that up and down (it had a fair amount of resistance) about 1/4 the track distance. I forget -- maybe it was at the top at first and I left it in the middle of the track. Anyway, put the lens back on and loaded the film and the camera worked perfectly. I fired off 10 shots and opened the camera -- yep, the film had advanced onto the take-up spool.
Now for some real film tests to see if it can actually take pictures... If so, then this is a real find -- one of the lightest SLRs ever made.