Dead battery = cluster problems?

[fuzzy530i]

It fixed itself thankfully. Knock on wood I haven't had any problems recently besides the keyless entry not working most days and sometimes its slow to start. I'm guessing it was the ignition switch after all but not sure. Now I'm chasing a bad sunroof leak that I can't figure out.

[JacobKnows]

Went on vacation for a week so my 02 530i sat the whole time. Car was running fine when I left but when I went to leave this morning the car wouldn't unlock with the key or the clicker. When I got home this afternoon the car unlocked manually. Took the battery to the parts store and it was bad so I bought a new one (13.6-8V while running, 12.26 with key on), I installed it and the car unlocked like normal. Started the car and the tach isn't working, temp gauge immediately pegs to red, yellow brake light is on, the radio will not let me set the time, the "fasten seatbelt" message wont go away when I click the OBC button anymore (only goes away when I put on the seatbelt), neither turn signal indicators on the cluster work, high beam indicator works if i pull back not push it forwards. If I turn the headlight knob to "on" instead of "auto" the high beam indicator works when I push it forward, regardless of the indicators on the cluster working all lights work as they should. The car runs and drives, only took it up the street and back so I know the ODO and speedo work but tach still won't. Sometimes when I turn the key to the "on" position the temp gauge will read correctly for a second then peg red.

Checked all fuses and they're good, did the cluster test and all lights come on and all gauges go through their range of motion like they should. When I check the coolant temp through the cluster it says -128 *C, and engine speed at idle through the cluster test said 65,XXX U/MIN.

Any ideas what's going on? TIA

Yeah unplug the ECU for about a minute or two then unplug the battery negative side first then positive leave disconnected for a minimum of two hours and reconnect give the car some driving time in the modules will start communicating and the cluster will start working after a few hours if you still have intermittent problems it’s probably going to be the passenger side airbag sensor has gotten wet