This page of the Ratchet & Clank Rift Apart game guide covers the first part of the planet Cordelion walkthrough. You will learn how to cross the platforms on the surface, how to switch between dimensions and how to access the underground part of Kedaro Station.
On Cordelion, similarly to the planet Blizar Prime, you will have to switch between two dimensions by using the blizon crystals. We decided to call the available dimensions the hot planet (inhabited, with characters above and below the surface) and the cold planet (abandoned, almost entirely filled with enemies).
You start in the hot dimension and must head out towards the central, largest platform surrounded by water on all sides. Position yourself on the large, square platform to be transported to the mission objective (you will find more of these moving platforms later while exploring planet Cordelion).
Expect to have to battle against Nefarious' machines. Depending on the type and placement of enemies, use weapons for short or medium range combat and try to target the "heads" of the machines whenever possible. You might also want to consider summoning your own allies to the battlefield (Mr. Fungi, Glove of Doom) so that you aren't constantly targeted by your enemies.
Use the ramps leading to the upper level of the central platform and expect more fights. Upstairs you will find Mrs. Zurkon, who has a new weapon on offer - the Cold Snap for 20000 bolts. It's a good weapon for immobilizing enemies and exposing them to the hero's attacks.
All enemies in the Cold Snap's area of effect are turned into ice cubes for a few seconds upon being hit. You can use this to attack them (with other guns or melee weapons) or to take a break from their attacks for a while.
Climb the stairs to the top. You will find a blizon that will put you in the cold dimension for the first time.
In the new dimension, you must set out in the opposite direction. In the previous location of the ramps, you will now slide back down, i.e. to the central level of the main platform.
Before you progress the main storyline, you might be interested in the eastern circular platform pictured in the screenshot, on which you can spot the blizon. You can use the Hoverboots to get there or you could bounce off the central platform and glide to your destination.
Once you have landed on the platform, you can hit the blizon and, upon returning to the hot planet, you will find a Gold Bolt. Grab it, then return to the cold dimension and step on the square platform to return to the central location.
Whether you are interested in the collectible described above or not, explore the central platform in the cold dimension and you will come across a working elevator. Use it to reach the middle level of Kedaro Station.