Halo:CEA speed reader help

Only need two or three more achievements for this game. Can’t seem to beat it on my own. help?

Turn on bandana and boom. Seems stupid but it’s how I did it. Begin running. Chuck grenades ahead of you. You die, you respawn. The timer fortunately respawns to the time of the last checkpoint, so you can take an hour doing the board. Just keep running and 'nading. You’ll get it eventually.