If you had the same brand & model both times I would get my money back, and try a new model.
However, if they were different models-I would check things around the home. Sometimes a glitch somewhere in the house can cause tv's and other appliances to burn out. (This has happened with my in laws-they went through two tvs, a stove, and a computer before they eralized the issue.)
Start weight after baby #3: 233.9
Current weight: 143
90 pounds lost!