Now at 1:59 it changes. Three walkup notes (each one repeating 4X) in bass to A A C A G F E on top. That's what it sounds like to me. Now that's enough for tonight.
I am watching videos of how to play keyboards and by ear.
Ah, this I can explain. In the chorus the single-note riff is replaced with root-fifth chords, or 5 chords; e.g, D becomes D5, some combination of the notes D and A. Varying from the original, I put the 5th of the chord as the lowest note; e.g., for D I used A-D-A. You’re probably hearing that low A.