I have a Beko oven and have verified that power supply is not the issue, by swapping fuses and seeing that the separate hob (which shares power) still functions.
Have you checked the main connection block where the power goes into the oven ?, Problems here are not uncommon on Beko cookers.
Please make sure that you isolate the power first.
live goes in and goes to the clock. it then goes to terminal p3 on the control sw. If it gets there make sure it comes out the other side of the switch when you turn on
neutral comes in and goes to terminal 4 on the switch. Also make sure it switches to terminal p2 when turned on