I need help

Hello, well... I'm going to be short, I have a Poco X3 pro, a week ago I was playing on it, and suddenly the Screen went black. I went to a tech and after a day or two he said that he couldn't figure what was wrong. If I put my finger on the lock button, it vibrates, like it's on, but no matter what I do, the screen stays black. I don't know what to do, is the cellphone just dead? I don't know, I just want some help, thank you!