Michelle A Brendel PhD - sealbeachrentals.com Potential landlord cashed deposit check and won't refund after no lease was signed Seal Beach, California

I filled out an application to rent a property owned by Michelle Brandel, and left a security deposit- it was understood she wouldn't cash my check until I signed the lease agreement- I called her to tell her I changed my mind and wouldn't be taking the apt.- she got very angry, and had already cashed my check, even though I never signed a lease agreement, and she never took the "for rent" sign down- she wouldn't give me my money back, it's been over a month now- what she did is Illegal, and it is a lot of money! $1795.00