During the fight with Zeruel when EVA Unit 01 loses all power, Shinji enters somewhat of a demonic state, stating the Angel give Ayanami back or face the consequences. After he says this, EVA Unit 01 reactivates and enters its berserk mode, thus starting its "awakening" process.
Now, this got me thinking, did Shinji himself activate EVA Unit 01's berserk mode in the heat of battle or was the timing just right for both EVA Unit 01 and Shinji?