WI Vote FAQ: What happens if a voter refuses to the sign the poll list?
If the voter refuses to sign the poll list, a ballot shall not be issued.
However, electors who have a disability that prevents them from physically being able to sign the poll list are exempt from this provision. If another person signed the voter’s registration form because the voter was unable to sign due to disability, the election inspector writes the word “exempt” on the signature line. If the voter is already registered but the voter claims to be unable to sign due to physical disability, and both inspectors concur, the inspectors shall enter the words “exempt by order of inspectors” on the signature line. If both inspectors do not waive the signature requirement, the voter shall be allowed to cast a ballot and the inspector or inspectors who did not waive the requirement shall challenge the ballot.
More at GAB FAQ