Conversation so far:
How did Dennis from the Beach Boys die?
He fatally drowned at the age of 39 in Marina del Rey while diving from a friend's boat.
When did Dennis from the Beach Boys die?
On December 28, 1983, he fatally drowned.
Was Dennis Wilson with the Beach Boys when he died?
With the rest of the band fearing that he would end up like Brian, Dennis was given an ultimatum in November 1983 to check into rehab.

Question: Did he check into rehab?
Self-contained rewrite: Did Dennis Wilson check into rehab after the Beach Boys told him to?