|The following is based on Creation Club content and is not canon.|
This quest begins with a radio distress signal. Track the signal to two rogue sentinel power armor units. This can be found near Drumlin Diner, south of Concord. After reading the sentinel system log, the Sole Survivor is directed to go to the propane station. Directly south of the federal ration stockpile, there will be an unmarked propane station. After defeating Dawson Wakefield, the passcode found in his inventory can be used to hack the powered down sentinel power armor.
Dawson is a legendary enemy and carries an automatic laser gun.
Another rogue sentinel power armor can appear in a random encounter after Malevolent Malfunction; it drops the Liberty Prime voice option for the sentinel power armor.