Someone has posted a video to go over the Halo comic which should answer the question behind the cracked helmet. Also the video may remember I am saying may revile some things about Halo 5. I am saying may because we don’t know about Halo 5 story will go so it is hard to say. If I have not turned you away yet check out the video below.
Article:http://gamingbolt.com/halo-5-guardians-comic-reveals-how-master-chiefs-helmet-got-cracked
As always thank you for reading.