How do I fix my hoover vision hd 8kg 1200 A+A washing machine?

My hoover vision hd 8kg 1200 A+A washing machines door security indicator light continues to flash even though the door is fully closed, it was in the middle of a cycle when the power went out in my flat and it's been like it since. This problem has been fixed at least twice before so it seems to be a recurring issue with this machine