Searching the robobrain and obtaining the Mechanist device may not complete the "Search the Robobrain" objective. [已核实]
You can move forward with the console command setstage DLC01MQ02 2400
You can uninstall Fallout 4 and DLC. Reinstall the main game and all DLC EXCEPT for Automatron. Load your current save, and then manually save the game. Then, proceed to reinstall Automatron. Reload the save file and the Automatron questline will restart from 'Mechanical Menace'. When that is completed, do not accept Ada's offer to follow you, this will then prompt you to send her to one of your settlements. Do not build a Robot Workbench. After sending Ada off, immediately proceed to 'A New Threat'. The game should be able to register the looting of the Mechanist Device from the Robo-Brain, and open up the next quest. Once this is done, then you may have Ada follow you and build a Robot Workbench.
If the player has built the Robot workbench prior to obtaining the prompt from Ada, the quest will not proceed until the current workbench is scrapped or stored, then rebuilt or placed again. Ada may be modified in other ways, but until the workbench replacement occurs, there will be no option to install the Special Mod that is the Radar Beacon. [已核实]
Attaching the radar beacon to Ada may not complete the "Install Radar Beacon on Ada" objective. [已核实]
You can move forward with the console command setstage DLC01MQ02 2900.
Upon first entering General Atomics Factory and begins to engage the robots, if the Sole Survivor exits the building, the Robobrain with the Mechanist device will spawn with the player outside.
It's possible that upon attempting to install the beacon, you may have limited options on Ada, including no "Special Mods" section, possibly due to damage taken during previous fights not fixing properly. If this occurs, attack Ada and kill her, then repair her with a robot repair kit. This will 'reset' her and allow full modification.