After leaving Diamond City, you will have to go towards the new green dot written on the map allowing you to enter Goodneighbor (picture1). Once inside this small town, take the left corridor and then enter directly into the huge building shown in the image below (picture2). You will then arrive in the building entitled: the Den of Memory (picture3).
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Once inside, follow Nick who will chat with Irma and then go down the stairs to reach a medical room where Amari will be waiting for him (picture4). You are free to explain your problem directly to him or go through Nick to explain your story to him (picture5). After implanting the cybernetic piece in Nick’s circuits, you will find that nothing happens... (picture6)
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You will have to sit on the chair to the left of Nick to enter Kellogg’s memory directly (picture7). The next main quest will tell you what to do once in Kellogg's memories in order to learn a little more about the kidnapper, your son as well as the hunters of the Institute.
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