Hendrikson was born into a worker's family, graduated from primary school in 1910 and went to work as a student of a locksmith at a paper mill. Until 1918, he worked in several industrial plants, and from 1914 to 1918, he worked as a locksmith at the wagon construction workshop at Dvigatel. A member of the Estonian Communist Party since 1917, in 1918, when the German forces invaded Tallinn, he left with the Red Army on a war ship to Helsinki, volunteering to join the Baltic Fleet. He served in Kronstadt on the ship "Respublika". He later fought in the 1918 Battle of Narva and the Estonian War of Independence for the Soviet Union. After the Estonian side won out, Hendrikson left for Leningrad. The Politburo of the Baltic Fleet sent Hendrikson in 1921 to study at the Estonian Labor Faculty in Leningrad. He graduated in 1924. During the summer he worked as a freighter on a cargo ship, traveled between England, Germany, Sweden, and Finland. He then entered Leningrad's F. Engels National Institute of Economics, where he graduated from the Industrial Department in 1929 and was sent to work as an engineer at the Leningrad Chemistry Department's Planning Department. The trust was reorganized in the 1930s to Lakokraska, and Hendrikson was appointed to head the economic planning department.