It seems like you understand that after pressing the reset button three times the primary control enters what is known as a hard lockout. To release from a hard lockout press the reset button for a minimum of 30 seconds or until you see the green light flash. That should release the burner from hard lockout.

There are several reasons this could occur (1) The fan motor may be defective and needs to be replaced. (2) The control or switch that operates the fan may be defective and needs to be replaced. (3) There is no power connected. (4) A switch is turned off or fuse has blown or a circuit breaker is tripped. (5) The fan blade may be stuck These are general reasons, depending on the air conditioner. There may be other reasons. In order to help I would like to know if it is a window, air conditioner, a central air conditioner, or some other type of air conditioner.