If your electric clothes dryer won't start or run even though the timer and control board are confirmed to be functioning correctly, there are several other potential issues that you can investigate:
Power supply: Check if the dryer is receiving power by verifying that it's plugged in correctly and that the circuit breaker or fuse controlling the dryer's circuit hasn't tripped or blown. If the dryer is not getting power, it won't be able to start.
Door switch: Most dryers have a door switch that prevents the dryer from running if the door is open. If the door switch is faulty or not making proper contact, the dryer won't start. Try closing the door firmly to see if it makes a difference.
Thermal fuse: The thermal fuse is a safety component that prevents the dryer from overheating. If the thermal fuse is blown, it will interrupt the circuit and prevent the dryer from running. It's usually located on the blower housing or near the heating element. You can test the thermal fuse with a multimeter to see if it has continuity or replace it if needed.
Start switch: The start switch is responsible for sending power to the motor when you press the start button. If the start switch is faulty, the dryer won't receive the necessary power to begin running. Test the start switch for continuity using a multimeter or consult a professional for assistance.
Drive motor: The drive motor is what physically spins the drum in the dryer. If the motor is defective or burnt out, it won't be able to turn the drum, and the dryer won't run. A buzzing sound when trying to start the dryer may indicate a faulty motor.
Belt or drive system: In some dryers, a broken or worn-out drive belt can cause the motor to run but fail to turn the drum. If you hear the motor running but the drum isn't spinning, it could be a belt problem.
Control thermostat or thermal cut-off: These components monitor the temperature inside the dryer and can shut it off if it gets too hot. If they are faulty, they may interrupt the circuit and prevent the dryer from running.
Electronic control board: While you mentioned that the control board is okay, there may be separate electronic components on the board that could be malfunctioning and affecting the dryer's operation.
If you are not familiar with diagnosing and repairing appliances, it's best to consult a qualified appliance technician who can identify the specific issue and carry out the necessary repairs. They have the tools and expertise to safely diagnose and fix problems with your electric clothes dryer.