Changing Batteries in Keypad

I had to change the batteries in the keypad that I use to open the garage door. I wasn’t sure whether this would require re-programming the unit but the answer is yes since the keypad could no longer open the garage door. So I followed the instructions on the inner aspect of the keypad cover - 
press learning button on motor
within 30 seconds, program keypad with 4 numbers
hold down Enter button on keypad until light above learning button begins to blink
when it blinks, release Enter button on keypad as the programming has been successful
However, in my case, the light above the learning button on the motor, simply goes out and does not blink and of course the garage door does not open with my 4 number pin. Any ideas as to why the light on the motor does not blink? This is the reason (I think) that I can’t get the keypad to open the garage door.