I have a belling electric oven that won't switch on. The fan element has been replaced as it wasn't working, but now we don't know what the problem is and don't really have the money to buy a new oven, or pay a huge price for the repair. Each time we plug it in, the internal lights flicks on and straight off, but the display doesn't work at all. The main element and thermos switch have both been tested and work fine. Please help!