The Lost Scout is a side quest in Mass Effect: Andromeda that you get to complete on Voeld. You get it from NPC Haana, found in the northeast part of the resistance base, once you unlock access to the base (after you leave Aya with Jaal on board the Tempest for the first time and complete Meet the Resistance). She requires help finding her friend Mashal and you will have to make a difficult choice once you find her.
How to restore power and open the door to the scout
Mashal is a demolition expert suspected to have died during a mission. Go to the waypoint Haana provides and you’ll see the destroyed site with some of the machinery still partly working. You can scan the big machine for some research points. There’s a small hill above the machinery that has the entrance into the ruins. Once inside you will see the door to the right that is locked, but survivors are in there. Go straight (if you scan the room you will see a power cable leading deeper into the compound) until you arrive to broken door blocking your way. You can destroy them with your melee attack. Activate the remnant console behind the broken door to activate power and unlock the room with the survivors.
Leave Mashal or make her go back to base?
You find Mashal with a kett prisoner and are presented with a staple Bioware dilemma. Let the torture continue with hope of Mashal finding her family (I’ll leave you here.) or kill the prisoner and have her go back to the resistance base (I have to kill them.). Let me tell you right off the bat that neither choice has any permanent consequence on the game’s story development going forward. Whatever you choose has to be in line with your own moral compass. In either case you go back to Haana and tell her what happened. She will send someone to pick up Mashal and that is that. Neither Haana nor Mashal appear crucial for the main story going forward. The only consequence is you living with your in-game choice.