A 39-year-old male office worker, previously found to be HBsAg(+) (1:256) with normal ALT during a physical exam 2 years ago, remained stable on follow-up. Presented with fever, fatigue, poor appetite, and dark urine for 1 week. Laboratory tests: total bilirubin (TBil) 51 μmol/L, ALT 260 U/L, HAV-IgM(+), HBsAg(+). The diagnosis is: