Objectives: Disable the disruptor field inside the Temple
Your main goal here is to make it to the roof of the Temple. Unfortunately, the door is locked at the moment, so we'll have to find a way to unlock it.
For now, look around. If you don't have a character with a high security rank, you'll have trouble with some of the doors here; there are quite a few DC 30 and 35 locks here. Don't hesitate to use security spikes, though; you won't need them for the rest of the game. You can also hack into a security console and use that to open the door to the armory in the northwestern corner of this level, at least. Speaking of the armory, you'll want to forge a path there before you leave this level; it's guarded by two Dark Jedi and a Dark Jedi master with some fantastic items on their bodies, like Sith power gauntlets (+3 to Strength) and an upari crystal (+3 attack, +1-8 damage). There's even a workbench in the armory you can use to reset your lightsaber crystals before you head to the top floor.
When you're done fooling around, head to the middle of the eastern side of this level to find the passage down into the catacombs.
Objectives: Unlock the passage to the Temple Summit
Hang a left after you take care of the droids here; you'll spot a rune-covered pillar surrounded by deadly frag mines. If you disable the mines here, you can pop a sapith crystal out of the pillar. The footlocker across the way holds a datapad, which you might want to take a look at before you reach the puzzle elsewhere on this level.
Did someone say puzzle? Well, this level's a tiny one, so you'll be on it in no time, and we mean that quite literally. You'll need to walk on the nine squares in order to unlock the door beyond; the tenth square, off to the side, is the game's reset button. If you follow the advice from the datapad, you'll learn that the correct route is to follow an H pattern, and thus you'll find the solution to be, from the perspective of the door that you came through:
After passing through the puzzle room, you'll gain access to a Rakata computer, which can unlock the doors to the upper level for you.