Great outcome, OP! Glad you came back to close the loop.
One tip for anyone reading this in 2026: California increased the small claims court limit to $12,500 for individuals (effective January 2024), so even larger deposits are covered. And there's been talk in the legislature about increasing the bad faith penalty multiplier from 2x to 3x for repeat offender landlords, though that hasn't passed yet.
Also worth noting that several California cities - including LA, SF, Oakland, and San Jose - have their own tenant protection ordinances that may provide ADDITIONAL remedies beyond state law. For example, SF's Rent Ordinance has its own penalty provisions for security deposit violations. So check your local rules too, not just state code.
The 21-day deadline under Civil Code 1950.5 is absolute. Courts don't give landlords wiggle room on this, especially when they can't prove they mailed anything. Keep documenting and keep filing - it works.