There is nothing in the law that requires Lowes to give you a refund. I assume your oven is like most appliances nowadays comes with a specific warranty, called an "express warranty".
When there is an express warranty then the seller and the manufacturer are only bound by those specific terms. Most appliances have a 90 day warranty that requires you to follow a certain procedure to notify the seller and the manufacturer in order to hold them liable. You would have to read the terms of your express warranty to know what your options are under that.
This also applies to any extended warranties that you may have purchased.
Assuming that you met the requirements for the express warranty and they should providing coverage, then your recourse would be to file a lawsuit in Small Claims Court. California has a state court website which has all the forms you need to file your case as well as an explanation on how to proceed in the small claims process.
The process of a lawsuit is essentially the same everywhere, with a few, minor procedural differences.
A lawsuit generally follows this process:
1) File the petition in the court with jurisdiction and venue. The court with jurisdiction and venue is usually where the defendant resides or has their place of business. You also have to look at the amount you intend to sue for to determine what court is correct
2) When you file the petition with the clerk of courts you will pay the filing fee and also ask for citation to be issued and service to be done. The clerk doesn't serve the papers so ask them if you have to take them to the sheriff's office for service or if they will do it. Just follow their directions as to that.
3) The sheriff will serve the defendant with the lawsuit.
4) The defendant will file their answer.
5) You can then do some discovery if necessary but you will need to check with the clerk and ask if your court allows discovery. Some small claims courts do not.
6) After that the next step is to set the case for trial.
7) During the trial you introduce your evidence and they introduce theirs.
8) The judge renders an oral judgment and a written order is made based on that oral judgment which the judge then signs.
That is the basic process of a lawsuit.
If your question has been answered then I'd offer my best wishes to you and ask that you please not forget to leave a 5 Star Positive Rating so I receive credit for my work. Of course, please feel free to ask any follow-up questions in this thread. I want to be sure all of your questions are answered.