I was soloing the Alderaan Star Fortress but shortly after destroying the three terminal things in the reactor room I fell off a ledge and found the way back was blocked by an impassable door. There seems to be no way to get back, and I'm not sure if I'm missing something, it's bugged, or the designers are just sadists.

 

If anyone knows what's up here I'd appreciate the help, because I'd really rather not have to start from the beginning because of something this asinine.

Bugs that prevent you going forward do occur infrequently, so it does sound like you've lost the 7 minutes progress.

 

When doing it solo I've had impassable doors that forced me to die and go to 'jail' but in group I've also had the impassable door syndrome as well and we had to re-start.

You can try traveling to your stronghold then back to odessen and re-entering star fortress. Generally when you have an active phase and leave you can pick up where you left off this way.