Then I solved the quest of the Ithorian in the flophouse by asking Fassa to buy some power cells off him, thus successfully transfering the quest to the 'finished' lot. After that, I finished the docking priorities quest.
Still, the power shortage quest remained open, and I had no idea how to solve it, so I peeked through a few walkthroughs, including the GameBanshee one, but found nothing. I tried Fassa's console again - this time there were no toggle options, just 'Log out'.
The problem is, while I was talking to Fassa about Lassavou's power cells, he said something along the lines of, 'Power cells? The pylons need power.' Logically, this would lead to the conclusion that, by making Fassa buy some power cells off the Ithorian in exchange for letting him go, the pylon power supply issues would be solved. Yet, the quest regarding power shortage is still open, and, as I said, I can't seem to find a solution to it.
Let's keep it short and simple: how do I solve Power shortage: bonus mission?