Legal Question in Landlord & Tenant Law in California

Since the unlawful detainer is an allegation that you have not paid the rent timely, if an agent of the owner accepts any part of the rent due, that makes the UD no longer valid. So the landlord must start the process a new and give you a new three day notice, etc.

Depending on where the unlawful detainer lawsuit stands, you might still be able to file your answer and plead that the landlord already accepted payment of the arrears. You might also speak with the landlord's attorney and advise her of the same information, and request that the case be dismissed. By the way, has the manager cashed your check? If not, and it's returned, you might still be in the same situation as before the payment.