Interview in Cantonese. First in with your direct boss technical manager, starting with self introduction and follow up some simple physics and materials questions to test your basic concepts in science and engineering sense. Ask you to brief introduce yourself in english, want to know if you can accept short-term business trips (1~3 times per year, 1-2 weeks each trip).
Second in with senior technical manager, prepare to be asked a lot of questions about your academic performance and fyp. They will challenge your fyp methodology/results with possible issues and want to know your problem-solving sense. Overall is not challenging if you know what you have done with your major and fyp.