Yes, both are possible.
With the first, he wasn't even a little angry. He was not angry at all.
With the second, you thought he was angry, but you have found out that he was not.
A: How did your dad react when you told him about your C in math?
B: He wasn't angry at all! He said he struggled with math and he's seen me work hard, so he knows I did the best I could.
A: What was wrong with Mark last night? He looks so mad!
B: I know! I thought so too. But I talked to him and it turns out he'd just been to the dentist and he was still numb. He wasn't angry after all.
Student or Learner