Hi Ya Kim,
The fault codes of F2 , F3 and F5 are indicating an oven sensor failure or the oven sensor circuit has loose or corroded wire connections. The oven sensor is a component that senses the oven temperature.
The oven sensor will have to be tested for the proper resistance to determine if it's good or bad. There is always the possibility of the oven control board being the cause of the fault codes as well, but most likely it's a failed oven sensor.
I recommend calling a hands on service technician to test the oven sensor and diagnose if it's the oven sensor or the oven control board.
You do not have to be afraid, just do not use the oven until it is diagnosed and repaired.
You will be safe until then.
Sear's : Contact us at 1-800-4-MY-HOME ® (1-800-469-4663)