How do I know if my logic board is bad on my garage door opener?

You can know if your logic board is bad on your garage door opener by checking several signs including no response to remote and wall button despite power, erratic operation, burnt smell, and diagnostic LED codes. First, check if opener has power, outlet has power, and breaker not tripped, if opener has power but does not respond to remote and wall button at all, no lights, no motor hum, logic board may have failed due to power surge. Second, check for burnt smell or visible burn marks on logic board, remove light cover and inspect board for blackened components or burnt odor indicating board fried. Third, check diagnostic LED blinking codes on motor unit, many LiftMaster and Chamberlain models have LED that blinks error codes, if LED blinks indicating logic board error or does not light at all despite power, board bad. Fourth, check for erratic operation like door opens or closes on its own, reverses randomly, or remote range very short, indicating board failing. Fifth, check if safety sensors have power but opener does not respond, as board powers sensors. Sixth, check if opener hums but does not move and gears intact, board may not sending power to motor. If opener is over 10 years old and repair cost of logic board 100 to 200 dollars is more than 50 percent of new opener, replace opener. Consult professional technician to test board with multimeter.