Legal Question in Criminal Law in California

Unless you are an attorney, YOU can do nothing for him but hire him an attorney and tell him to to exercise the 5th Amendment right to SHUT UP and do NOT talk to ANYONE about the case except his attorney. It is already too late for him to refuse consent for the search, and the evidence they found will not likely be "thrown out". He may have already 'blabbed' to the police about the facts.

Of course he can still fight it. Raise all possible defenses with whatever admissible and credible witnesses, evidence, facts and sympathies are available for legal arguments, for evidence suppression or other motions, or at trial. He faces potential prison / jail and fines, so handle it right. Not exactly a do it yourself project in court for someone who does not know how to effectively represent himself against a professional prosecutor intending to convict and jail you. If you don't know how to do these things effectively, then hire an attorney that does, who will try to get a diversion, reduction or other decent outcome through plea bargain, or take it to trial if appropriate. If serious about hiring counsel to help in this, and if this is in SoCal courts, feel free to contact me.