A/C board had corrosion on it

First I unplugged the A/C. Then I removed the two screws from the front cover. Next, I removed the srews holding the front board. Then I removed the screws from the metal box which house the second board. Removed the second board and replaced with the new one. Final I did the same process backward. Less than fifteen minutes from beginning to end. Plugged the A/C in and turned it on. It's been work fine since.