Gta5 question about avenger mission? On the ps4?

Play gta5 on ps4. And now I've been stuck for days on doing the mission of Lester, where you have to steal the Avengers from Hangers. No matter if with 2 or 4 players in the team, not yet done. Have some good advice or trick on how you did it. Do not get ahead there

Play defensively and before you start the mission, fill up all snacks and buy the heaviest armor.

Hay, armor and snacks are always full for me, but still nothing to do. Or I'm too stupid, I'm sure I'll be killed 50 times a day, with my vehicles and weapons, somehow zero chance. That is already annoying