Buttons stopped working
If yours still zooms in all the way when you turn it on, then I had a similar problem with mine. When I turned it on, the camera would zoom out all the way and the other buttons wouldn't respond. If I switched it to review, it would just cycle through all the pictures, so I figured somewhere the zoom lever was stuck inside. I don't know a lot about cameras, so I sent it in to Panasonic (it was still under parts warranty), but was informed that due to "grit substance" my warranty was voided and it would cost $179 to repair. Since I could buy the same camera used at www.keh.com for that price I told them to send mine back and I'd take a shot at fixing it (since I was pretty sure it was a mechanical problem).
Here's what I did with a $1.79 glass repair screwdriver.
Remove the battery and take out all the visible screws on the outside (2 on the right, 1 on the left, 3 on the bottom). Lift the back panel at the bottom edge, and it should pivot along the top edge until you can remove the back. Then unplug the two ribbon cables (the small one has a latch on top and the larger one has a black latch on the side that you need to lift). BOTH have hinges, not just the smaller one like other posts have said.
Next you need to remove the front panel. There are three silver screws placed around the lens unit (look down inside, and you'll see them attaching it to the front panel). Remove these, and you should be able to remove the front (lift at the bottom and it pivots along the top edge). Now you should be able to pop off the top cover (with the zoom, power, etc). Now if you look at the bottom, there are two screws holding the board to the cover, remove these and you've got it apart.
On the top right side of the board, you'll see where the external zoom switch pushes a very small black lever. This was where the problem with mine was, the black lever was stuck over. You can use the tip of the screwdriver to pop it back to the center position. Now make sure that if you push it one way or the other that it will recenter on its own. Mine didn't, so I had to pop the small silver cover off where the lever is with the flathead tip of the screwdriver. Be careful here. The lever just sits on a peg, and has very small gears that move a slide bar. If either of these fall, you may never find them again.
I took both the lever and the slider off, cleaned them, and got it so it would recenter easily again. Then I put them both back in, popped the cover on (you may have to pry out one of the sides slightly to get it back on), and the lever works fine now. I wouldn't be surprised if your camera has this same problem. If it's something else, it's still probably a problem with this mechanism that you could fix.
Anyways, reattach the board to the top cover, and pop it back onto the camera. Now insert the battery, and turn it on to see how it works. Even without the screen, you can try the zoom. If it all works, then all you need to do is put it back together in the opposite order you took it apart. When reattaching the LCD ribbon cables, make sure the hinges are open, insert the cable, and snap down its latch.
Hopefully that works. I don't know much about cameras, but it wasn't too hard. Just work slowly and carefully.
