F7 error code references an issue with the buttons (shorted key) on the electronic oven control board. Unplug the range for 3 minutes to reset the electronic control board and then restore power. If the code returns, replace the electronic control board.
Check the connections first to make sure they aren't burnt, frayed, and are connected tightly. If the connections are fine, you'll need to change the control board.
Here's the control board: searspartsdirect.com/product/49hj1sl5ju-0022-364/id-wb27k10090
You can find parts and diagrams on Sears PartsDirect: searspartsdirect.com/model/3y7i2tepxs-000582/kenmore-36275621301-gas-range-parts
How to replace a gas range oven control board DIY guide: searspartsdirect.com/diy/repair-guide/how-to-replace-a-gas-range-oven-control-board
You can call Sears Home Services at 1-800-4-MY-HOME for repair.
(I am not sure about the '40'. It could trying to tell you that the F7 error code has occurred 40 times.)
Hope this helps!