This chapter is a complete guide for the quest connected with Cauldron RHO. Here you can find tips that will help you to finish this quest in the most beneficial way.
Beginning the quest
The mission is added to your journal only when you are very close to the Cauldron.
When you are close, the only thing that is left to do is to eliminate all roaming machines. When you approach the Cauldron's main entrance, on the right you can find a chain of bushes. You can use them to lure the Watchers.
You quickly learn that the Cauldron's main entrance is blocked. Go to the torch on the left and go down to ruin's lower levels.
You get to the place where you must jump down and use the rope to rappel down. When you do that you can't go back to the surface so be sure that you have all necessary supplies.
Go to the Cauldron's Core
Keep going down until you can enter the mountain. Enter the Cauldron and you can quickly find the doors that needs to be overridden. Interact with them and move forward.
There is one Watcher in front of you that can be quickly eliminated. Behind the machine you can find an unusual turbine. By shooting the blue part in the center  you can change the direction in which it moves. Shoot it and the turbine will move clockwise. Now, stand by the ledge and face the turbine's ring. Catch one of the glowing handles  and keep holding it until the ring takes you to the other side.
Move further into the Cauldron. There is a bigger room behind the next door. There, you must face Watchers and one Ravager so try to eliminate at least part of them while being undetected.
Next, go to the platform on the left from the entrance. Change the direction of the first turbine  to make it move clockwise. Grab one of the handles and use it to get to the turbine's top. The platform that allows you to get further into the Cauldron is far away and it is impossible to get to it just by using the turbine alone. So, when you are at the top, jump and Aloy can catch a cargo  that moves on the assembly line. Wait until you are right above the platform and let go of the container.
Create a bridge by using override and catch the next turbine. This time you don't have to jump while grabbing the ring. The ring overlaps with the platform. When you are on the other side use override again to continue the quest. The passage on the left is now open so you can access Cauldron's next rooms.
In order to do that you must go back to the first turbine in the room. This time catch a container above you but don't release it until Aloy gets closer to the next barrier. When you approach it release the container and use small stairs to go up. Here, the turbine is horizontal and in default it moves counter-clockwise. Shoot the blue part and grab a handle. By doing that you get to the other side. This allows you to continue your exploration.
You will very quickly find another Watcher. Move forward after eliminating it. In the room you can find two weaker machines. You can search through the room if you want to find a few supply chests. One of them is on the top of the handles  presented on the picture. If you want to move forward, you must override the door . If you decided to use the handles then, from the upper level, you can also access the next room, the same one behind the door. It is easier to shoot the machines from above so if your level is low it is a much safer way.
In the next room you can find five Watchers, two Longlegs and a Ravager so shooting them from the above is a better choice than an open conflict. Especially because you should keep your med pouches for the fight with the last enemy in the Cauldron.
After eliminating all machines go on the platform on the right from the interaction point and create a bridge to get to the interaction point. After using override go to the next room that became accessible after turning off one of the electric wall's segments.
There are two turbines on the right. You must jump from one to the other if you want to get to the point required to continue the quest. Be sure that both are moving counter-clockwise.
Go forward. For a moment, keep the right side but then you must quickly jump to the left part of the platform. When you are there, proceed further into the Cauldron. In the end you can find another bridge that can be activating by using override. There are no enemies nearby.
Defeat the boss and override the Core
You must jump down to get to the last room. Behind it you can find the same place as on the picture. Eliminate or override the Watchers that gathered on the bottom. Next, turn off the force field.
In the final fight you must face Snapmaw and Ravager. Both machines are vulnerable to fire. You should use the fact that setting Snapmaw's back on fire can cause an explosion so shoot a few arrows at this weak point. If you manage to do that, the range of explosion can damage the Ravager, which allows you to reduce its health points. Remember about dodges, especially when facing the Ravager.
After the fight you can override the Core and go back to the surface. The quest is now completed. Now, you can override all machines that were the part of the Cauldron to which the Core belonged.