How do I get someone who understands mobile maintenance for all devices and has experience?

You ask for a technician who has the required experience to repair different types of mobile phones and their faults, and search the applicants based on the experience they have provided. Then you can interview them and give them a practical test on several faults for several mobile phones, or you can agree with them that there will be a trial period of a month or three months, for example, and based on that you can determine who among them is suitable to work with you. Thank you.