Security Deposit Return Issue

My landlord is attempting to withhold $500 of my security deposit for a pet violation that allegedly occurred in early February. There is currently no documentation of the alleged violation, nor was there a notice sent at the time of the alleged violation regarding a cure to the issue. What should be my next move to address this?

My current idea: ask for the evidence of the violation & the notice that was supposed to be sent with the violation.

Would I have a chance in court if the landlord continues down this path?