Former MK Dons midfielder Keith Andrews is to take up a full-time coaching role with the club this season.
Midfielder Gary Deegan has signed a new one-year deal at Southend.
The 20-year-old Chilean has failed to make an appearance for the Red Devils following his arrival from Universidad de Chile two years ago.
He spent five months on loan at Wigan in his first year in England and last season went to Spanish second division side Real Zaragoza, where he scored six times in 25 appearances.
"I am happy with my arrival at Dinamo, with whom I want to do good things," Henriquez told the Croatian club's website.
"I have a lot of motivation and I want to prove myself and I believe Dinamo is a great club for it."