First you need to notify the California State Licensing Board about the fraud and the use of your license without your permission. That will at least give you some defense should a license claim be filed in the future for defective or deficient construction.
Second, you need to notify in writing all of the various companies that you know they are doing business with under your license about the fact that they are not authorized. Obviously, you need to notify your former business partners to cease and desist their deceptive trade practices - again do this in writing.
You have identified several causes of action here and would be entitled to seek damages. The problem would be that these types of cases are expensive to litigate and at the end, your former partners may just hide under a rock and your judgment may be effectively worthless.
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There are many ways those who defrauded you may be held accountable. The two main ways are a civil lawsuit and criminal charges. Your civil case may be quite strong but if the defendants have no money than the case will not be appealing enough to an attorney who might otherwise take it on a contingency (where he gets paid from a share of the recovery). Perhaps you can persuade the police or the district attorney to look into this fraud. Unfortunately, they are often overworked with other crimes and may be unable to take up your cause.
One other option might be to provide evidence of the fraud to the bond or warranty companies. I don't understand your facts very well, but it sounds like warranty claims were paid out and a well-funded company may be interested in pursuing the bad guys - or may have the connections to have criminal charges brought.
Yes, some firms provide pro bono services to clients without adequate resources to fund legal services. There are also community outreach programs that provide pro bono attorneys to the less fortunate.
Gather all the documentation and contact an experienced attorney to prepare a formal complaint to the California State Contractors License Board and to consider possible criminal and civil action. If your name is on the license, consider putting it into inactive status. Your attorney cannot threaten criminal or administrative action to gain advantage in a civil claim, but those actions can be pursued nonetheless. If this was a sole proprietorship of yours, you may be personally liable.
Fraud occurs where a party has, through deception or misrepresentation, caused another party to change his or her position in reliance on the deception, and caused damage. There are different species of fraud that exist in a wide array of contexts.
These comments are for general informational purposes and do not create an attorney-client relationship. Do not rely on this post as "legal advice." Consult with a licensed attorney regarding the specific facts of your case and your rights and liabilities.