I believe the following query in Andrei's post:
update users set authority_id = (
select authority_id
from auth_authorities
where enabled_p = 't'
) and user_id = your_user_id_here;
should be
update users set authority_id = (
select authority_id
from auth_authorities
where enabled_p = 't'
) where user_id = your_user_id_here;