Michael Ellement has posted this draft on SSRN.  Here is the abstract:

Despite strides in the modern-era, voting continues to present barriers for persons with disabilities. Many in the disability rights community saw promise on the horizon with the passage of The Help America Vote Act (HAVA) in 2002. HAVA focused on updating voting machines across the country, and additionally enacted standards for disability access to voting locations. However, HAVA failed to contain a private right of action to remedy violations. As many commentators have discussed, this failure to permit persons aggrieved by violations of HAVA to sue for those violations has left many of HAVA’s promises unfulfilled.
Under-analyzed is the potential use of § 504 of the Rehabilitation Act (RA) to enforce voting rights for persons with disabilities post-HAVA. The RA’s § 504 prohibits any “otherwise qualified individual with a disability” from “be[ing] excluded from the participation in, be[ing] denied the benefits of, or be[ing] subjected to discrimination under any program or activity receiving Federal financial assistance . . .” The RA provides a private right of action, for damages, to parties aggrieved under § 504. This includes suits against state agencies and government, as § 504 contains a valid exception to the doctrine of sovereign immunity.
This Article suggests that § 504 may provide a de-facto private right of action for enforcing the promises of HAVA.