Final answer:
The associate should first empathize with the customer's situation about the toy fire truck's lights and express a willingness to resolve the issue.
Step-by-step explanation:
When a customer approaches the service desk with an issue about a toy fire truck's light not working, the associate should first show empathy and acknowledge the customer's inconvenience. A suitable response could be, "I'm sorry to hear that the lights on your son's fire truck are not working. Let's take a look and see how we can resolve this issue for you." This initial response demonstrates good customer service by addressing the customer's concern and setting a positive tone for the interaction.