Get the 4th Fuel Cell
From the campfire, head northwest. Be careful as you make your way north, the ground can sometimes fall out under you if you aren't fast enough.
It's safer if you head northwest and stick to the path near the water's edge. There will be a couple of enemies, but no unexpected turrets or falling ground will inconvenience you.
As you head northwest, you will soon run into a campfire near the West Coast Fishing Village where you can rest at.
From the campfire, head northeast and then southeast, making your way towards the fuel cell icon on the map. You will eventually reach a ramp you can climb up to reach the Hydroelectric Dam, and a campfire to your right.
Proceed to the right of the campfire and a cutscene will play, as you note the fuel cell is under water. This starts the Open The Floodgates sidequest, where you need to find a room with a pumping mechanism.
The room you are looking for is to your left, with a yellow terminal inside. As you approach the door, it will be locked and you need to look for the keys for the room.
Head east of the terminal room (on the map) and you will find another building connected to a pipeline. Inspect the clipboard inside the building on a table to find that the workers lived in Fjord Village and the key could be there.
Head east and climb up the stairs near the pipe. Break the crates blocking your way and head northwest. You will soon find yourself in Fjord Village. Head to the northern-most house with a sink and a clock buried in snow to the left of the sink. Search the sink to find the key you need.
Return to the dam terminal room and you can now unlock the door. Use the terminal to drain the water and a cutscene will play, showing an automatron in the center of the lake.
You can't just jump in (the fall will likely kill you), but there is a safe way to enter the newly-drained area. Head east of the dam terminal room and make your way around the lake. When you reach the south/southwest part of the lake, you will see a ramp you can go down to safely reach the automatron in the middle.
If you want to rest at a campfire/save beforehand, you can lower a drawbridge west of the ramp to easily get back to the Hydroelectric Dam campfire.
Inspect the automatron in the middle of the area to begin a fight.
This battle isn't too different from the fight against the Crown in Solaris. There is one glaring difference though; the Sword uses a flamethrower which can quickly deal a lot of damage. The flamethrower will be a threat throughout the battle since it can easily kill you if you are caught in it for more than 3 seconds.
Otherwise, the attacks are largely the same. It shoots orbs and stomps in the first stage, uses missiles that rain down in the second stage and adopts a turret stance in the final stage. It can also shoot missiles that track you, similar to what the Law used, but only if you're far away.
The same strategy of circling and attacking will be essential, especially with the flamethrower being used. Being mobile at all times is very helpful in this battle.
If things are getting too hectic and you need to heal, there is a ruined car that you can hide behind (and a large rock) that can absorb the impacts of the orbs. It might not be perfect at absorbing missile/flamethrower damage, and you need to pay attention in case attacks get through.
Otherwise, not a fight you haven't seen or dealt with before.
When the automatron falls, grab the final fuel cell. Return to Canaveral and install the final fuel cell. Inspect the escape pod and it will teleport somewhere else, but the Undercrown East entrance will open. That is your next destination.