The first thing that this manager needs to do is to gather more information. It is not enough for her to know that the products are not succeeding. She needs to know why they are not succeeding.
The first thing she needs to do is to determine whether the products are defective. If they are, she needs to determine where the production process is going wrong. In other words, she needs to conduct quality control experiments.
If the products are coming out the way they are supposed to but are not selling, then she needs to find out from the customers why they chose not to buy the product her company is making. By doing this kind of market research, she can find out whether her company's product does not meet the needs of the customers or whether the product is good but her marketing and sales people are doing a bad job.
Overall, she simply needs more information so that she can determine what changes need to be made.