I've gone to the embassy and I've seen the cutscene but everything stops there. Is there something else I'm supposed to do? They mentioned going down in a cave somewhere, but there is no mention of anything in my mission log.
Take the transporter to the underground ruins (it has its own pad) and talk to the Romulan civilian standing there, from whom you get the actual mission. Then go to the entrance to the underground ruins.
What's the point of keeping two consoles active anyway? I thought it would fail the mission, when I lost all four consoles, so not sure what the purpose of it all is here. Nothing in the wiki about it, so not sure on that part, despite the mission completing anyway.
Actually you don't even need to touch the ruins until T5, and as it's a major pain in the tail, I'd recommend doing exactly that. For the record, saving the plant from overloading netted 5 more marks the one time I managed it around the mass of Tholian spam.