Hi, thanks for using JustAnswer.com. Your relay on the board has welded itself together, causing the F1 code. You will need to replace the oven control. May I please have the model number and I will get you the part number you will need?
The control is number 2 in the attached diagram, pat number 74008098. I believe your model number may be MER5870AAW...
That part is available at http://www.myapplianceparts.com/ or at your local parts retailer.
Yes, this part is easily replaced. It is accessed from the back of the unit. Be sur to unplug or flip breaker before removing the cover, though. You will see the control as soon as you remove the back cover. It will be held in place by (4) screws. If you remove the control and install the new one, THEN switch wires, one at a time, you will have no problem doing this yourself...and saving approx $100.00 or more!