The bracket that connects the push arm of our garage door opener is getting ripped off from the door (see picture below). All screws, except a bolt at the top of the bracket are detached. How can I fix this if I do it myself?
If cosmetics are not important to you, it would be useful to mark the bolt locations and drill through to the outside. Adding external bolts with washers to spread the load would return the bracket to near-original operating status.
If cosmetics are more important than noted above, a strong adhesive would enable the forces to be spread over a greater area than the original installation provides.
A polyurethane adhesive such as Gorilla Glue would give strong bonding, but you'd have to have some way to compress the bracket against the door while it sets.
It's difficult to determine from the photo, but you may have a wood garage door. In that case, you should remove the painted surface under the bracket to provide a better bond for the adhesive you select.
Epoxy adhesives with longer cure times, upwards of 30 minutes, will provide more strength than the much weaker five minute versions. Apply an even layer of glue and secure the bracket as firmly as possible to the door.
I would consider that a bracing timber, such as a 2x4 of sufficient length could be used to apply pressure to the bracket while the adhesive sets.
Returning the bolts to the original location, with additional adhesive in the bolt holes will also help.
You might be missing the point.
Most people have only ever pushed buttons and never actually lifted a garage door, so it's easy hold the belief that a garage door is a massive 200 pound behemoth that can only possibly be opened with a burly machine. That's absolutely untrue.
Garage doors are balanced by their springs. Opening forces are only a few pounds. When a power opener lifts a door, it's more like walking an old lady across the street. At least when things are working.
Before openers, if a garage door was having problems, you'd know it immediately because you'd feel it bind, and you'd fix it early. Now that we push buttons, the lifter just muscles the door through the defect, which of course does nothing to improve the situation. Eventually the lifter stalls, the lifting arm breaks, or the door tears itself apart. That last case is super bad: Since doors amount to a spring balanced against gravity, doors contain lethal amounts of energy at all times. If a door fails, it can kill you.
So when a lifting arm breaks, that's your deity looking out for you. Think of a weak lifting arm like a fuse that protects your wiring, or like the spillway that protects the dam. You don't want to defeat that.
Fix your door.
Something is binding seriously in the door. The door is trammed due to a broken lifting cable, a spring has broken, rollers are off their track or seriously damaged, etc. Focus on that.
I'm assuming the panel in the middle is thin so I would drill four holes in a square pattern into the bottom flat section of the bracket and fasten to the door with wood screws. I would do the same at the top flat section of the bracket. It looks like the top of the bracket is tucked under the metal brace at the top. If that brace has pulled out at all drill holes in that every four inches to fasten it back to the door.
I've had a similar repair necessary after a cable to the door spring broke. First things first, with the garage door closed disengage the opener's carriage by pulling the cord connected to it. Then by hand open and close the garage door feeling for any defects or excessive weight. If there are any anomalies, have them fixed. To fix that bracket, I used two pieces of perforated angle steel bolted through the original bracket and door panel.