When you’re hunting down Fia or visiting her facility in Fristad Rock, things can heat up pretty quickly if she catches you and thinks you’re after her in Deathloop. She’s not sentimental and is willing to detonate her reactor within the facility before she lets you get to her. The object is a major hazard, but you can disable it to ensure it’s never a problem during your loop.
Before taking on the reactor, you want to visit Fia’s workshop to find a schematic of the reactor. With it, you’ll be able to know the correct way to disarm it. Without it, you’re shooting in the dark, and missing means you’re going to deal with a massive explosion.
You can find Fia’s workshop on floor zero. It’s going to be next to the elevator shaft that you can use from the rooftop entrance of the facility. It’s to the left of the elevator, locked behind a door that you can hack, next to a sensor. However, you can also break the window to sneak inside. At the back of the workshop will be a reactor blueprint that shows you the order of the wires you need to cut to prevent the reactor from going off.
Once you have that information, you can proceed to the reactor at the center of Fia’s complex. You can find it underneath her room. It’s a large missile-like object. If the alarms ever go off at the facility, you want to go straight here and hack the panel behind it to access the wires. You then need to cut the wires in the correct order that was shown on your blueprint. For us, it was the red, green, blue, and then yellow wire. It could vary for you on your playthrough.
After you’ve done the correct order, the reactor will no longer be an issue. However, this does reset after every loop, but you’ll know the combination moving forward.