You may want to have an attorney dig into this a little deeper. It is not clear from your post whether or not the property is exempt from the Los Angeles Rent Stabilization Ordinance.
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With that qualification, under the City of Los Angeles Rent Stabilization Ordinance (RSO), if there is internal access between the units, then it may be considered a single family home and thus exempt from the RSO. (There are other exemption which may also apply based upon the date of construction of the property, i.e. after October 1, 1979.)
However, even if the property is otherwise exempt as a single family home, if your landlord fails to annually register the unit with the Los Angeles Department of Housing (LAHD), the landlord is not entitled to collect rent. Having a valid certificate of occupancy is a prerequisite for registration with the LAHD.
Finally, under Civil Code 1950.5, the landlord is supposed to return your security deposit within 21 days of termination of the rental agreement and provide an itemized breakdown of any deductions for unpaid rent, cleaning and repair of damage beyond normal wear and tear, including receipts for any materials or third party services plus the hours and rates for the landlord's employees used. If the landlord retains your security deposit in bad faith, you can recover treble damages.
Further, if the landlord fails to comply with Civil Code 1950.5, the landlord is required to refund your entire deposit. Granberry v. Islay Investments (1995) 9 Cal.4th 738, 745. However, in an action to recover the security deposit, the landlord may cross claim for damages to the property and/or unpaid rent.