North Country Ford Lincoln

We purchased a 2013 Ford Escape from Luther North Country Ford. They told us they did an 'all-points' check on the vehicle before we drove it off of the lot. One week later the battery was dead. We lifted off the battery cover and everything was corroded! They did replace the battery free of charge, but I sure would like to know if they do an 'all-point's' check why this wasn't discovered. We never really got an answer when we asked that question.