Stuck in the Riot Guard section

[ThatPoster]

I got into my first Riot Guard suit, and at first everything seems fine. But now I keep dying because I don't have enough health, when I restart the checkpoint I only have one box. I'm just past the section where you have to get out of the suit to open the door. When I continue from there it gets difficult because there are multiple other robot guys and I get slaughtered when I try to go through them. How am I supposed to do this section with one box of health?

EDIT: found out you can go to an earlier checkpoint in the main menu. Went in again and strafed while I shot them to pieces. Got through it no problems.