C-50 will not turn on (shooting mode)

If it tries to move and fails, then you have a lens problem.
Likely a crack (invisible to the naked eye) in the outer barrel.
Usually lets the ball bearing fall out of it's groove between the
two barrels. Rattles a little if you gently shake the camera. Almost certainly needs the lens assembly replaced.

If it doesn't even try, but the rest of the camera operates normally, then I'd guess you're looking at the interconnection(s) between the mainboard and the lens motor(s). Connector pulled apart, cracked mainboard, or something.

you say that "Now it will not work at all" If it doesn't even try and the rest of the camera is dead as a doornail, then perhaps the battery connections? Power board?

It would help to know the history of the camera. Was it dropped, sat on, or at the beach? Was it working then suddenly stopped?
I've worked on a lot of digital cameras. To determine the problem with the zoom, disassemble the camera down to the lens module. Try to isolate the extension-retraction circuit and drive the motor from an external source. Usually you'll find the lens has broken tracking tabs on the main group barrel or retrofocus converter group or the ways or guides have cracked. I recently repaired a Nikon 4100 that responded nicely because the guide elements just snapped back into place. Usually they snap and break off or are already broken off because most are plastic. Some older ones are aluminum and can be bent back into shape but that takes quite a lot of experience. Sometimes there's just a piece of grit in the ways and you can revive it by complete disassembly and cleaning. Otherwise you might be looking on eBay for a parts camera with a good lens or mainboard.

Good luck

Plastic lower door track is broken allowing the door to lift disengaging the toggle under the door this toggle is what controls the lens opening.. Impossible to fix but I have designed a replacement piece of hardware that will fix it,I have started to maching a few and I intend to sell them on ebay my email is jarg1@verizon.net.....J