Though the Fire and Flames

I don't know about whatever GH game you're talking about, but i beat it by holding down green and instead of tapping the buttons and holding the hammer on, i just tapped each botton and strummed each note that wasn't green. After the strum i'd really quickly let go of the button so both that button and the green was hit. That made it so i didn't fail.

Score wasn't very high though, lol.