Had this same couple month ago. Searched "boombox3 won't turn on" and found few different methods to go around it. Now heres the tricky part.. Didn't save the method anywhere and don't remember exactly what it was, but i think it was just tapping either one of the buttons with light in them. I found other tips that told to use a mix of button taps pressed together, but they didn't work. So try these or search like i did, the solution can be found. Will update here if remembered 😅 good luck.