I'm sure lots of people on here are interested in why no warranty repair?
Looks like you might fix it under and beside the sink and water heater.
You'll need to do a lot of research before starting.
Have you ever worked with PEX plumbing? It's not hard to work with, you'll nned some SharkBite connections and maybe a couple short pieces of PEX.
Hopefully somewhere near your water heater you can cut and swap the line coming out of the water heater and the cold line.