I had the same issue. I plugged and unplugged the cooker any number of times and pushed every button. Display only showed SEl X. Hoping for a reset, I left the cooker plugged in overnight. It did reset itself and is working perfectly now. The program buttons work, and it heats up immediately. There is no practical explanation or logical steps. I hate throwing things away. Never give up!
They don't have fuses they have thermal cutoffs. It would be located at the heater. You'll just have to try to take it apart to find it. Purchase a cutoff from any electronics supply shop in your area.
The answer to your question is yes. See page 3 for a diagram which shows how the lid gasket fits around the inner outside edge of the lid. Do not however block the vent holes.