Trouble Brewin'

Trouble Brewin' is a side quest in Fallout 4.

Detailed walkthrough
The quest is received either by speaking to Rufus Rubins in Goodneighbor's Hotel Rexford, or from independently finding Buddy at the Shamrock Taphouse and interacting with him. When asking Rufus for work, he will ask the Sole Survivor to retrieve the Drinkin' Buddy, a protectron modified to function as a microbrewing machine, from the Shamrock Taphouse and bring it back so no one has to keep drinking the barman's normal swill.

There are raiders both inside and outside the Shamrock Taphouse. The raiders inside include a raider boss named Gaff located upstairs. There are also some radroaches in the kitchen closet and several mole rats down in the basement.

Buddy can be found in the basement, inside a protectron storage container, locked with an expert level security terminal. There is a note on Patrick's terminal that says he's stashed the password down in the basement – the password is on top of the shelves underneath a flashing red light. To reach it, either jump onto the shelves from the stairs leading down into the basement or hop up while pressing against the corner shelves.

One of the entries on Patrick's terminal indicates that the robot may be a bit frail and expresses concerns about transporting him to the buyer. However, this does not translate into the gameplay as Buddy will always arrive at his destination in one piece. The Sole Survivor will have to choose to either send Buddy to the Hotel Rexford as agreed with Rufus or to send him to one of their settlements. Escorting Buddy is not required and the player character may choose to fast travel to the final destination and meet Buddy there. The quest marker will not update until Buddy arrives in Goodneighbor.

When Buddy arrives at the Hotel Rexford, Rufus will express his admiration and pay the Sole Survivor the agreed-upon caps, completing the quest. Buddy will henceforth be established as the new bartender and the Sole Survivor will be able to ask him to tell them a joke, receive a daily batch of beer from him, ask him where to find additional recipes, or store any Gwinnett or Nuka beverage in him which will turn ice cold after 12-24 in-game hours.

If the Sole Survivor chooses to keep Buddy for themselves, the quest will not be completed until Buddy is sent to the Hotel Rexford. If Rufus is killed at any point before this, the quest will be marked as failed and removed from the quest log.

Bugs

 * If the player decides to send Buddy to Hotel Rexford, and Buddy makes it to Goodneighbor by himself without being escorted, he will be waiting outside the Hotel Rexford. After the player talks to Rufus, the quest hangs at "Bring Drinkin' Buddy inside the Hotel Rexford". Talking to Buddy will not get him to enter or follow you into Hotel Rexford, and he stays in his "Introduction" loop; he cannot be exchanged with or given more recipes, even if the player has read the recipes in their Pip-Boy.
 * The quest can be completed, even if you choose to keep Buddy, by opening the console and entering . You will then be sent to the last stage (speaking to Rufus) as if you had sent Buddy to the Hotel Rexford. Alternatively, you can use . This gives you the reward Rufus promised you and completes the quest.
 * If Buddy still provides the dialogue choice to be sold to Rufus after the quest completes you can change this with the command . The dialogue choice will permanently change to "No thanks" and helps prevent the player from accidentally re-assigning Buddy. Even though Buddy's home destination is Hotel Rexford, he will then head back to the Shamrock Taphouse. If the player returns to Hotel Rexford and uses to get Buddy back to the Hotel Rexford, Buddy will still return to the Taphouse afterward.
 * If the player decided to keep Buddy when first encountered without the quest and sent him to a settlement the quest may become broken and can't be completed as Buddy will set the home parameter back to Taphouse and will not move to Hotel Rexford.
 * After talking to Rufus in Goodneighbor, ask Buddy where to get more recipes; he will respond by asking if you want to commence delivery to Hotel Rexford, in which case you should say "I am keeping you for myself." Ask him again for more recipes and now choose the option "I've sold you." He will then continue to Goodneighbor.
 * To avoid this, the player (if without the quest from Rufus) must not send him to a settlement if decided to keep him as of this moment the home parameter is still set to the Taphouse. Get the quest from Rufus, then tell Buddy to move to Hotel Rexford, at this stage the home parameter will be set to Hotel Rexford. The player is then required to escort Buddy to the hotel, after which the quest should complete properly.
 * This bug can be fixed with the use of console commands. One can reset the quest with the command . After that, it is advised to follow the steps detailed above to avoid any further issues.
 * If the player decided to keep Buddy after telling Rufus he would send him to the Hotel Rexford, one optional objective completes, but the quest remains in the log stuck on (Optional) Send the Drinkin' Buddy to the Hotel Rexford.
 * Attempting to send Buddy to Hotel Rexford results in Buddy accepting request but not going. Talk to Buddy again and tell him you're keeping him for yourself, give settlement destination, then doing Hotel Rexford dialogue again will get him to go.
 * If the player decides to send Buddy to Spectacle Island he will get stuck in the water and never arrive at the settlement, causing the quest to glitch. The only way to resolve this is to kill Rufus to fail the quest.