I'm really sorry, I don't want to frighten you, but he really does sound very ill. Most people resolve HBV without symptoms, but for others it's definitely no trip around the park. My husband has cirrhosis from chronic HBV, so I know a little about it. Those are pretty late-stage complications you describe. However, I'm hesitant to say much, because I think there's so much variation in causes, results, treatment, etc. Your brother's case should really be discussed with him--and his doctor, if he has signed a release. You definitely need to start there. If you have specific questions, I can try to point you in the right direction. In the meantime, you could google hepatic encephalopathy, portal hypertension, jaundice... and of course HBV itself.
I wish you and your brother the best.