From The LNR Book of Knowledge

Rewards: Modified Fusion Reactor Schematic

Start: Buried Tablet (“Inpsect”), [2916,1410], Berken’s Flow Jedi Ruins, Mustafar

Part 1: A vault? - Secret vault [1750,1214]

Part 2: Disabling the security system - The following instructions are given once arriving at the vault:

• Turn the left Dial to 8 (“Turn to 8”)
• Click the saber symbol on the Holocron (“Click saber symbol”)

Part 3: A hidden treasure, the choice - Choose between the left or right Lever on the vault; Radial menu: “Pull lever”; The outcome and reward is the same for pulling either lever

Part 4: The ancient guardian - Combat: Guardian Droid (CL78); Spawns if you pull either Lever

Part 5: A strange schematic - After killing the droid you will get the reward