Recover Account Access

My cousin gave me his Ring Doorbell after he was unable to install it and I promised to (someday) look into the matter. Then he died (April of last year). I have his Ring account email address and its password. What I do not have is his email password (got lost); thus, I cannot complete the two-factor authentication. So, what to do? I obviously have documentation (Letters Testamentary - I am his heir). Thanks