Stimulus ssi and registration

I have a client who receives ssi and hasnt filed in years. I tried to help with signing up for the registration, however it was rejected and given a reject code for  Persomal identification pin.  My client has no idea about a pin and if he ever had to identify fraud or apply for a pin. He has not been able to reach anyone at the IRS to request his pin. What can he do? I know he can file a paper return but his only income is SSI that is non taxable.  He is a disabled older man with 2 dependents.