Pyrosphere door glitch

The Pyrosphere door glitch, also known as the Sector 3 door glitch or Locked Door in Sector 3, is a potentially disastrous bug in Metroid: Other M involving a locked door found in the basement of the Desert Refinery, which completely halts progress, leaving the player unable to continue without starting over or using an old game save taken before the bug occurred. Consequently, copying the save files to the other does not solve the issue. Nintendo later acknowledged the glitch and revealed its cause. If the player encounters this glitch but does not wish to start over, a fixed, non-glitched save file of this door for the US version is available for download. 
==Cause==
After escaping the Vorash chasing her in a vast cavern, Samus enters the "Pyrosphere combat arena", a room where she must battle a group of Zebesians and Novas before receiving authorization to use the Ice Beam from Adam. After that, Samus will reach a long corridor which locks her inside. To unlock the doors, Samus must defeat a group of Dessgeegas. Once all Dessgeegas are defeated, the doors will be unlocked.
Should the player, for any reason, backtrack at this point to the "combat arena" where Samus first used the Ice Beam, the door in the basement of the Desert Refinery will remain locked permanently, and the player will not be able to continue on further in the game. The door is located at the basement exit after the three Grapple Points.
To avoid the glitch, the player must exit the room via a newly unlocked door near a tall cliff down at the end of the corridor, and proceed as normal before doing any backtracking to any previous rooms.
Nintendo set up a program allowing those affected by the glitch to send in their save data on an SD card so that their data would be fixed.
==Nintendo Official Guidebook for Metroid Other M==
The Japanese strategy guide for Other M includes an editor's note warning readers about the glitch, and explains the location, cause and how to avoid locking the door. The letter translates as follows:Translated by Leah Hicks: https://twitter.com/loohhoo/status/892133681120325633
METROID Other M
Note Regarding Inability to Progress To Sector 3
--- Symptoms ---
The door to progress to the next room is still locked red, and you cannot go back nor move forward.
--- Location ---
In the highest floor in the Desert Refinery, after defeating the boss, and across from the three grapplinghooks in front of the elevator exit of the ground floor, there is a door on the other side.
--- Cause ---
At the beginning of the game, after acquiring the Ice Beam, there are two rooms ahead which containenemies that have two spikes. After eliminating them, if you do not proceed to the door just ahead (in the center of the screen) and instead attempt to return (behind the screen) back to Sector 2 (to theroom where the Ice Beam was acquired) then try to progress forward again, the above mentioned problem will arise.
--- How to Avoid the Problem ---
After acquiring the Ice Beam, do not attempt to head back to Sector 2 once you have killed the two-spiked monsters, and simply progress toward the next door (in the center of the screen).
==References==
Category:Glitches
Category:Pyrosphere
Category:Criticism of Metroid: Other M