Speed, rpm, water temp, fuel not working

A while ago I changed my oil pressure sensor because it went bad. After that my speed, rpm, water temp, fuel gauges stopped working along with my ac controls, and even my brake lights. Just wondering if anyone can give me advice on where to look for the problem. Lights, turn signals, radio, and what seems to be the non electrical gauges like oil psi, air psi, air suspension all work. Also, when I turn key to on all seems to work fine. I turn it on and it works for like 20 seconds and that's when it all stops working. 2000 peterbilt 379 cat 3406e

 

So I looked inside the cluster and the battery discharge protection system beeps when I turn it on and once it stops beeping the problem starts? Is it bad wiring causing the batteries to drain? I made sure the batteries are tightly connected but idk what else to check. Can that little box go bad as well, the battery discharge protection system?