Already figured out the 5 blinks. Motor must have overheated while checking last night. I unplugged unit and replugged and blinking has stopped with no change in the travel of the door down. Any thought?
To answer your question here as to why the machine may have overheated and/or why the problem went away after unplugging it is that Chamberlain machines have a built in thermocouple that will disable the unit to prevent further damage (overheating the motor, blowing the starting capacitor, etc.) And sometimes unplugging the machine reboots the system and clears out the "ghosts in the machine." It's kind of like rebooting your PC - it will sometimes make minor issues go away.
HOWEVER, with that being said, if your door comes down on it's own manually or slams to the ground, your springs need to be adjusted by a professional. As the previous poster said in your other thread, your door is NOT balanced. Which means that your machine is doing double duty to lift that door. Not a huge deal, but you will wear out the machine prematurely.
Contrary to popular belief, the springs do all the work, the machine just gives the door the initial push and pull. And, if your door has 2 springs instead of only 1, the second spring is not there as a "back-up" to be used in the meantime until the broken spring can be replaced. If 1 spring breaks in a 2 spring setup, the door will again be out of balance and the remaining spring will be doing the work of both springs, decreasing it's life cycle as well.