After activating the terminals in Divine Beast Vah Medoh, you can activate the Main Control Unit and battle Windblight Ganon.

First Phase

Run away from the tornadoes that Windblight Ganon creates. If Ganon shoots energy blasts at you, you can try to knock them back at Ganon with Perfect Guards, but if you have trouble with this, just hide behind obstacles instead.

You can shoot at Windblight Ganon's eye to deal damage. Use the updrafts to make use of the slow motion effect while aiming.

Second Phase

After Windblight Ganon has lost 50% of his health, the second phase begins.

Run away from the wind blasts, tornadoes, and energy blasts that Windblight Ganon shoots at you, or hide behind obstacles to avoid them.

Windblight Ganon may aim a red laser at you, then will shoot an energy blast. You can try to deflect these with Perfect Guard, but if you have trouble, just run away from these attacks.

Attack Windblight Ganon the same way you did during the first phase of battle.

After

Get the Heart Container after the battle, then activate the Main Control Unit. After the cutscene, you will have Revali's Gale, which you can activate by holding X. You can disable Revali's Gale from the inventory menu in the Key Items section.

Go up to the elder's house in Rito Village and talk to him to complete the Divine Beast Vah Medoh quest. Then open the chest beside the elder to get Revali's Great Eagle Bow.