Run and jump up through the door using SpeedBooster in the room below. Bonk the door frame as you pass through the transition, to cancel your horizontal momentum. You need a vertical speed of exactly 7.8800 when passing through the transition, which requires the jump to be frame perfect. After the transition, as you reach the wall, begin holding right. Begin holding angle up at any time before approaching the door (and you can continue holding it until the end of the strat). As you approach the door (an 8-frame window), while holding angle up, release right for exactly one frame. This will put Samus into a pose aiming diagonally up and to the right. Immediately fire a shot to open the door (within the same 8-frame window); if successful, you will just barely clear the grapple block and pass through the door. Several things can cause you to bonk the grapple block: 1) entering the room with too much vertical speed, 2) not pressing against the wall as you come up, 3) releasing right for more than one frame, 4) releasing right too early. As an alternative to releasing right for one frame, you can instead press shot for one frame: if successful, Samus' pose will change to aiming diagonally without a shot being fired; if shot is pressed for more than one frame, then a shot will be fired horizontally, and the cooldown will prevent you from firing diagonally in time.