You'll need to open the dryer up in order to locate the main circuit board at the top of the machine. Once you have access to this, you will need to check that mains power is reaching this board. (Obviously you will now be at risk of being exposed to mains voltage and hopefully take the usual precautions to avoid electrocution!) My guess is that you will find no voltage where the mains power connects to this board - best use a multimeter to determine this. If this is the case you will need to check for loose connections at the board or damaged wiring down the line by tracing the mains power supply cables. If you are at all unsure about this type of electrical work please employ a qualified engineer to do the work.
As a side note, it may be more economical to replace the machine than pay for an engineer service call. Additionally your machine was subject to a manufacturers recall as they where prone to catching fire. Beko should have fixed this fault free of charge if your machine was one of those affected. Best look into this if you decide to repair your dryer and you have not had this recall work already done.
Rupert
December 2019