I just went through this exact situation in my building last year and wanted to share what worked. Our board tried to levy a 12,000 dollar special assessment for elevator modernization without a membership vote. We organized the owners, demanded a special meeting under Davis-Stirling (Civil Code Section 5610), and forced a vote.
The vote actually passed, but here is the important part -- during the process of challenging it, we discovered that the board had not been conducting a reserve study as required under Civil Code Section 5550. California law requires HOAs to conduct a reserve study at least every three years, and the board must distribute a summary to all members annually. Our board had skipped two cycles. This meant they had been underfunding reserves for years, which is why they needed the special assessment in the first place.
We used this as leverage to negotiate a 24-month payment plan with zero interest. The board agreed because they knew their failure to conduct reserve studies was a breach of their fiduciary duty. We also got them to agree to hire a professional reserve study company going forward and to create a reserve funding plan that would prevent future emergency assessments.
For anyone facing a similar situation: always start by requesting copies of the most recent reserve study, the board meeting minutes where the assessment was approved, and all bids for the work. Under Davis-Stirling, you have a right to inspect these records within 10 business days of a written request (Civil Code Section 5210). If the board refuses, they can be liable for a 500 dollar penalty per violation plus your attorney fees.