Charge Doors are a new type of Door introduced in Metroid: Samus Returns. As the name implies, they can only be opened with the Charge Beam, after which they become regular doors. If Samus attempts to shoot them with an uncharged beam, the lock will briefly light up, but not be removed.
It is strongly implied that Charge Doors are actually Doors that have lost power and that the energy of a Charge Beam shot is enough to restore power and function to the door. This is further implied by their presence in tunnels that previously were flooded with the corrosive purple liquid and near superheated rooms, and confirmed by Metroid: Samus Returns Official Guide. In addition to the Charge Beam, the Beam Burst can also be used to restore power to Charge Doors, though this can be viewed as an unnecessary use of Aeion.
- Inhabitants & Eco System of SR388 (p. 26)
- "The same age that has worn down a lot of inactive doors has also done a number on some Beam Doors, turning them into Charge Doors. Charge Doors earn their name because they've lost power and need to be reenergized. In your case, the Charge Beam gets the job done (and gives anther meaning to the name "Charge Door"). Once a Charge Door is charged, you never need to recharge it, but these doors definitely cause a nuisance early in the mission."