I can't complete the Old Guns quest. I am up to the point where we need to test the artillery, but throwing smoke grenades does nothing. There is an NPC assigned to the artillery, and the transmitter has sufficient power, but the NPC assigned to the transmitter claims it does not have power and will not sit down and operate the transmitter. I noticed he was standing after I cleared out the tunnels beneath Castle, but that was some 10 hours of gameplay ago.

I uploaded video of the issue on YouTube. The video title is "Fallout 4 Old Guns transmitter bug on PS4".

After searching via the Internet extensively, I have come to the conclusion this is a very common bug with no current patch/fix. Many just reload a previous save and pick up a few steps prior so as to avoid the bug. Unfortunately for me, I got distracted and went off gallivanting to do more quests and 40+ hours later, this is not a feasible option for me.

Hopefully a patch will be released soon, and meanwhile I will make the best of it with many other very entertaining quests, though I really would like to progress this particular quest line asap.