Whirlpool Free Standing Gas Range YKGRT607HS5 Timer Repair

We recently got a used Kitchenaid selectra electric oven from some friends. Worked fine for two months then last night we were cooking a pizza and it was at 400 degrees and cooked the dough. Put back in with the toppings... said still 400 degrees with both elements on showing but actually nothing on, and range top did not work. Electronic clock, and clock work, as do the auxillary 120 volt plugs. Breaker was not off (obviously) but I thew it anyways. Nothing. Unplugged and reset the clock still no go. Suddenly about an hour later (I kept trying it) the oven started warming up and the top elements worked... set it for 450 degrees but it only made it to 400 before suddenly shutting it all down again. Now as before only the clock and clock and auxillary plugs work. Pretty sure I have to replace the control boards but cannot find a schematic on line and I do not understand how to remove the side plastic pieces to unscrew the top panel and get at the control circuitry and yes it is unplugge

Oven wont start F-4 indicated on display???