An opener that hums while the door stays shut is usually fighting a broken spring, a disconnected trolley, a bind in the tracks, or a side lock. Stop cycling it. You hit the wall button. The opener hums. The door does not move an inch.
The motor is trying. The door is not traveling with it. The cause is usually not "a dead opener." It is whatever sits between the motor and a balanced door. Sort the forks before you buy a new head.
If the door feels like a brick
On a lot of homes that means the spring above the door is broken, so the opener is trying to lift a door that suddenly weighs a few hundred pounds. You may have heard a bang earlier. You may not have. Either way, do not keep hammering the button hoping it will muscle through.
Pull the emergency release only if you need a second check and you can stand clear of the opening. A balanced door still moves by hand with steady effort. This one feels like dead steel. Look at the coil above the opening. A gap in the winding, a collapsed spring next to its pair, or a slack cable on one drum are common clues. Do not climb a ladder with winding bars. That energy can injure you.
If the opener runs and the door sits like furniture
Sometimes the emergency release got yanked and the trolley never locked back onto the rail. The opener runs along the chain or belt. The door sits there. Look at the red cord and the carriage on the rail. If the opener head is busy and the door is dead still, that disconnect is a common culprit. See how to get the red cord to catch again.
Close the door by hand first if you can. Follow the sticker diagram on your unit, not a random video for a different brand. If the door already feels like a brick when you try to move it, stop. That is spring territory again, not a trolley click.
If one side looks crooked
A roller hanging out of the track will also pin the door. One side sits farther out. The motor strains. Stop using the opener. Do not kick the bottom panel. Do not stand under a hanging door. Do not shove the roller back in with a screwdriver while the opener still has power.
Ice in the bottom of the track, a flared rail from a side hit, or a cable that went soft on one side can put you here. The hum is the motor fighting steel that will not give.
If a side lock or vacation switch is still on
Some doors have a slide bolt or cane bolt through the track. Some openers have a lock button on the wall control that ignores remotes and sometimes the outdoor pad while the motor still answers the indoor button in odd ways. Check the obvious physical lock before you assume the spring failed. If the door will not budge by hand even a little with the opener disconnected, treat it as bind or spring, not a lock.
What it is not
This is different from an opener that grinds like gravel while the door creeps along. Grinding is often a chewed plastic gear inside the head while the door still travels a little. Here the door stays put. The hum is the motor spinning without a clean lift.
It is also different from a door that starts closing then climbs back up. That one is usually eyes, travel, or force on the way down. Here the door never left the closed position, or never started the open at all.
A door that hangs stuck halfway while the opener tries is mid travel bind.
What not to do
Do not climb a ladder and mess with winding cones on a torsion spring. Do not cut cables. Do not force the door up by hand if it feels much heavier than usual. Do not keep cycling the opener hoping luck will fix a bind. Each wasted cycle cooks a motor that may still be fine once the door is balanced again.
I am not a contractor. This is what shows up when the opener sings and the door ignores it. A shop that works on garage doors will check the spring, the trolley lock, the tracks, the side locks, and the opener drive before they sell you a motor you did not need.
Safety notes on openers and disconnects live on DASMA's garage door opener page.
The U.S. CPSC garage door operator page covers federal rules for automatic openers.
If the door is stuck and you want someone local to look, get a quote.