Car will not start after battery replacement

My interior light was left on for 4 days and this made the battery drain completely. Fob was also not working. Opened the door manually. Tried starting but all lights were not working. We tried doing a jump start but the car will crank without start. All lights and A/C come on fine during the jump start. We bought a new battery but same issue. Also the car won’t communicate with a diagnostic reader when plugged to the OBD. Plus, surprisingly, the mechanic just informed me that the brake malfunction message (little screen on the dash) came on in his garage. Please any help will be appreciated.