Macbook Air boot loop after update

Hi there, I posted this in the MacBook Air section but since it’s a problem that happen after an update figured I’d post it here to and see if anyone has an idea

Hi there, my brother had me look has his MacBook Air, bought it this summer and I’m pretty sure it has OS Sierra. He performed and system update, computer clean doesn’t really have anything on it, upon restart it’s black screen, Apple logo, gets to full then glitch and restarts and continues to do that, tried holding shift key and command r etc nothing happens. Any help greatly appreciated