The 665 the model number prefix means it's made by Whirlpool. F7 means it has a problem with the control board or keypad.
The first thing to try is a "hard reset". Unplug it from the power line for a minute, plug it back in, set the clock, then try again.
If it still has a problem, we repair these for customers nationwide with our guaranteed $39.95 service. If a new keypad were needed, that would add about $60 to the repair cost.
Please feel free to contact me directly if you need more help.We're happy to help and we appreciate your thoughtful rating of our answer.
William E. Miller, AS-EET[email protected]http://www.microwavedisplay.com