this one took me ages to figure out cuz in the video he has his guitar dropped down a 1/2 step..
it goes
[Bm7]Trouble com[A]es knocking I'll be ready al[C#m7]right
with my[Bm7] fists up ready to fi[Bm7]ght
But i ain't gotta put my fi[A]sts up e[E]veryti[D]me
the Bm7 is hammered on from a barred 2nd fret..
the E is played open and the D is played barred...
just repeat that riff throughout..
it goes
[Bm7]Trouble com[A]es knocking I'll be ready al[C#m7]right
with my[Bm7] fists up ready to fi[Bm7]ght
But i ain't gotta put my fi[A]sts up e[E]veryti[D]me
the Bm7 is hammered on from a barred 2nd fret..
the E is played open and the D is played barred...
just repeat that riff throughout..