There isn't much to go wrong in a digital kiln. The system is simple and easy to understand. The components:
1/2 amp fuse: helps to protect the controller
transformer: sends 24 volts AC to the controller
controller: decides when the elements turn on
thermocouple: sends temperature reading to the controller
relays: receive 12 volt DC signal from the controller telling the relays to turn on the elements
elements: heat the kiln
Once you understand that basic system, you can understand digital kilns of all brands. And once you understand how they work, you can fix them yourself.