Ok.. Just try running the garage door by pushing the button and see if it catches the latch just fine. It will probably be just fine.... What your friend was trying to tell you to do is to grab the garage door and manually open or close it to catch the latch back onto the chain. You don't want to pull on the red cord when you are doing this - just grab the bottom of the door and either open it or close it to catch the latch. You REALLY don't want to do this with all your strength - or you might break something in the garage door latch.. It's usually harder to open and close the door - so it takes some strength to open it up without the help of the motor... but you want to go slowly when it's hooking the latch back up or you might break that part. Here's what is going on.... The Red pull handle thingey has a spring loaded latch inside it... kinda like how a door knob works. That latch grabs onto the hole on a plate connected to the door opener chain - and the garage door goes up and down when the motor runs. (It holds together like how a door latch holds a door closed) When you pull the string - you just pull the latch out of the hole in the metal plate connected to the chain.. like how turning a door knob lets you open a door.... and you can manually pull the garage door go up and down without the motor moving the chain. Does this make sense...

From your description it sounds like when you came back to close the door after mowing something was blocking the safety beam or perhaps you bent the safety beam mount with the mower?? Anyway pulling the cord only disengages the door from the Genie screw and not from power etc. Stopping after 5 minutes is probably a heat sensor shutting the motor off. I would call the installer back and try to have a reasonable discussion with him. There probably isn't much wrong if anything. The manual is a good source of information but not very interesting reading.

There are two roll pins that hold that gear in place on the shaft. You only need to remove the bottom one and the gear will slide off. It will take a punch and hammer.

Okay