Cal. COM § 10514

(a) In rejecting goods, a lessee’s failure to state a particular defect that is ascertainable by reasonable inspection precludes the lessee from relying on the defect to justify rejection or to establish default: (1) If, stated seasonably, the lessor or the supplier could have cured it (Section 10513); or (2) Between merchants if the lessor or the supplier after rejection has made a request in writing for a full and final written statement of all defects on which the lessee proposes to rely. (b) A lessee’s failure to reserve rights when paying rent or other consideration against documents precludes recovery of the payment for defects apparent in the documents.