You will not get any specific answers here, how are we supposed to know what your panel should do ?
I am involved in FAT tests that can last from 1 hour to 2 days, each one is different and has to be custom written depending on the functionality required by the customer
Your customer has asked you to build a panel to fulfill a task, write the test round the functions and demonstrate they work gaining your customers approval on each function\outcome of the test.