I think the Help button is mostly for reviving fallen allies to stabilize them and give them 1 HP so they can rejoin the fight.
I haven't tried it recently, but I know the last time I tried it, it did not do the Help function of giving advantage to an ally.
Can anyone else confirm?
The last time I played, when I used the Help button, I believe the character was only downed and not dead yet. Not sure if it gave it advantage but only 1 HP.