I'm not wanting to sound demeaning, but here goes.
Do you know how to use a volt meter? When set to DC volts, use the two probes and ground the black lead against a well grounded bolt or metal piece. Using the red lead, check to see if there is power at fuse 14 on both sides of the blade ends on the top of the fuse.
I'm a teacher, so this is how I'd instruct my students to do so.
Here is most of the information that I think you are likely to need.
WATER INGRESS AND SOLUTIONS
It looks like you have a problem with the floor harnesses or grounds or the CCM, you can get this fault with or without water ingress.
Locate and fix source of water ingress, if any.
I suggest you completely unwrap all of the CCM harness and pull the wires apart to find the splices, any corroded splices need
to be cut back, soldered, and covered with marine grade heat shrink tubing. (You might need to add short wires to replace what you cut out)
Also check ground connections (1 on floor and on "A" Pillar), and check CCM/TCM and "A" Pillar connectors.
You do need 2 keys. Test: You must be able to lock the driver’s door with the key and have the red led alarm light next to the lock button blink. If it does not blink, the alarm does not know the door is closed and will not go into matching mode. If it does blink, it is working properly, you can then proceed.
Put one key in the ignition switch, turn ignition on, do not start engine. Close the door,(you are outside of the car) use 2nd key, turn door lock and hold in lock position for 10 seconds. Release key to neutral position.
Press and release a button on the remote, wait 2 seconds and press the same button again, the turn signal lights will flash.
This indicates your remote matches the car system and is now recognized. Unlock the door with the key, remove the other key from the ignition. Have all keys and remotes in your hand. Close the door. (you are outside the car) Remote should now work
Remotes DO NOT WORK with the ignition on or if a key is in the ignition switch. They only respond during matching with the ignition on. If you have more than one remote, you must repeat the procedure and REMOVE the key from the ignition each time. Removing the key from the ignition finalizes the procedure.
You can remove the door lock cylinder, and then use a screwdriver to activate the lock.
Or you can get another key cut. (This key will not run the engine unless you get it matched by a dealer or VW registered locksmith)