I have the stylus 840. When turning it on the lens comes out and goes right back in twice, then the "alarm" sounds 4 times and then it turns back off.

I'm afraid you have a defective camera. Or the sensor is defect, or the connection to the sensor is not good. (lose, oxidised, broken or lots of other stuff) also the main board can be defect. If also the pictures come out (on the computer) dark and pink, I.m afraid you have to start saving for a new camera.
Make sure the lens is clean and not greasy.

Try these procedures.

Replace the caps

Maybe a gear tooth broken in reduction mechanism.

The internal plastic gears which govern the lens opening and closing are either damaged or out of alignment - this happens when a camera is dropped or has any other form of physical interaction for which it is not designed.

Good evening, The lens of my camera Olympus 840 remains blocked in open mode, it does not close even device turned off. I can not take a picture or even view the pictures taken, no buttons is functional. Thank you in advance for your help.

I just bought my stylus 840 olympus digital camera in aruba one and half weeks ago. Charged the battery and it worked fine for the two times I used it. Now it won't turn on. I charged the battery. Even bought a new one and nothing happens.

I have had this issue on several Casio camera the lens comes out fine and then goes right back in some times it just gives you two beeps and nothing else. the problem is with the lens its focus motor is out of ajustment. According to Casio this is not covered under any type of warrenty coverage and that ****.but hehe sometimes you can take it back to places like bustbuy and if you have your receipt they will sometime swap it out. But lets say they don't. well you sometime can get a replacement lens for it off ebay for pretty cheap. This is only if you are sure that you can fix the camera. If you choose to have it fixed make sure you shop around there is a huge diffrence between shop to shop.

Sounds like the lens can't get into the proper position. Any possibility of damage to the lens?