The Green Light door is one of the doors that you will encounter in Metroid Dread. The amount of green light on the door is the same number of switches you have to shoot consecutively to unlock it. You need to get the Storm missile first to be able to unlock the Green Light Door.
How to get Storm Missile
You can get the Storm Missile after you defeat the boss Escue. This boss is located in Ferenia and it is an Electric flying bug that has quick attacks. You need to keep dodging its attacks while getting a few hits in to win. After defeating the Bug boss, you will get the Storm Missile.
How to open Green Light Door
After getting the Storm Missile, press R to activate the skill. This will charge up your Storm Missile. Aim on the green switches all over the room and once you are locked on all the green switches, press Y to launch your Storm Missile.
After pressing Y, your Storm Missile will launch and hit all the switches on the wall. Once they all turn red, the switches on the door will turn red as well, unlocking the door.
READ NEXT: Metroid Dread: How to Break Pink Block