Airpods 2 aren't connecting

My airpods are not connecting to my phone. I've tried everything as possible, the 15 seconds wait, pressing the buttons for 10 seconds. My friend put my airpods 2 in his case, took it back out, and put the airpods back into my case. I tried putting my bluetooth on but it's just not connecting. It's not connecting to my friends bluetooth either. How do I fix this?