Garage door opener on wall shows excessive closing force detected,error 4 - 1---when I push button to close door it does so but opens up immediately again.

SOURCE: Door will only close when held down

That normally happens when the sensors aren't aligned. Both sensors have led lights on them the yellow/orange one will stay on all the time the green one will go out if it cant see the other sensor. Possibly theres a wire that's broken or the other sensor is really out of alignment. Check every inch of wiring from the sensor to the opener, remove wire nuts if present and check the connections. The wires that are used are small, solid and can break easily. Also see if there's a staple that's too tight, move the wire abit where it's stapled and look for damage.

SOURCE: Chamberlain Garage Door Opener will not close door

It is most likly your sensors You should not have to mess with your force settings but I can help you with your sensors assume you have checked to make sure there both looking at each other. First close the door so you can see them better. Tap each one of the sensors to see if any of the lights are flickering. if your then you need to tight them up and try again. Also when its dusk or night close your garage door and look at the lights see if one of the tracks is shaking sensor. If not check the wires make sure there is not staple or cuts in them. Then last thing you can check see if your door is hitting the back of the sensor mount it does happen. Also remove and ropes or handles you have fromt eh buttom of the door. That should take care of the problem. Make another post if your still having problems

SOURCE: My garage door opener won't close the garage door.

Most likely your door sensors have been bumped and are not aligned properly. Make sure they are pointed at one another and the small light on each one is lit and not blinking.

SOURCE: my craftsman 1/2 hp garage door starts to close and then opens up

I had a simular issue, except mine was that the previous owner decided to mess with all the settings and mounts and screwed everything up.

The problem isn't your force sensors its your downwards stopping sensor on the opposite side of the opener. For me I had to take the entire panel off and replace the sensor back in its holder, but try adjusting that sensor setting (clockwise goes down, counterclockwise goes up).

If that doesn't work then i dunno:)

Also set both force settings in between 0-1, for some reason with mine if i set it higher it would set them off....

SOURCE: After a lightning storm, my LIftmaster Formula 1

If when the door reverses the main light flashes 10 times you have a problem with the door sensors. Make sure they are pointed at one another and the small light on each one is lit and not flickering. They must be pointed at one another for both lights to be on. If you cannot get the lights to come on you have a bad logic board.