Good Evening melvia, thank you for your post!

Based off the information you have provided your Frigidaire range is displaying an error code of “F9” and the door lock light is on. An “F9” error code stands for runaway temperature (overheating). This could be an issue with your RTD (Resistance Temperature Detector) or the EOC (Electronic Oven Control). I would recommend performing a reset on your oven and you can do that by disconnecting from your oven for ten minutes. If you continue to have issues with the “F9” error code I would recommend having a professional technician out to your home for proper diagnosis and replacement of any electrical components because it could be a problem with your door latch or control panel. Hopefully this information has been helpful. –OOS