You can speak to a medical malpractice attorney for free as they almost always are contingency fee based, meaning that they take your case at no cost to you; they only collect if they recover on your behalf.
I suspect what you signed was not a pre-op waiver of liability, rather just the regular old informed consent forms. Even if you did sign a pre-op waiver of liability, I doubt that it is enforceable in California.
You can speak to a med mal lawyer for free, so do it.

