guys, my iphone has got a weird problem. whenever the battery reaches below 20%, the phone just dies off completely. I WILL NOT BE ABLE TO RESTART THE PHONE/ HARD RESET, or whatsoever.

The only way to turn it back on is to charge the phone. And when the phone is back on, the battery would be at 3% left?

Was wondering whether i could send in for warranty claim though?

SERIOUS HELP NEEDED. ): THANKS.