[DanGPrice]

2018 G30 540i XDrive. I was installing an AMP and SUBWOOFER in the trunk of my BMW. Trunk was completely disassembled so that I could access Factory AMP and battery. Backseat was disassembled so I could replace rear deck speakers.

Everything went smooth. 4 speaker wires that went to back deck speakers is what I tapped into for the sound to my amp. New AMP is wired straigt to the Batter in trunk, both positive and negative.

Everything was wired and mounted in it's permanent location. We tuned the AMP for sound quality after all wiring was secured and remounted.

I am still using the factory amp, I simply tapped into 4 wires (rear deck speakers) - AMP has 8 guage wires going straight to battery. So everything is completed and everything works, we were done! All that was left to do was to reassemble all of the interior panels that had been removed.

Turned car off & started replacing interior panels. No issues replacing panels. Once car was reassembled, got in it to leave and noticed radio was not working. Hell, tons of stuff isn't working.

Here is what I know:
I have a bluetooth OBDII reader, I use it with Bimmercode & Scantool
Scantool still works - I had NO CODES before we started this process (other than gesture camera failing)
Now I have alot of codes (listed at bottom)
Bimmercode can not connect to the ODBII device any more.
Turning car on: NO CENTER SCREEN. A/C CONTROLS DON'T WORK, vents lightl blows heat.
Radio obviously doesn't work, yet the amp I installed STILL HAS POWER GOING TO IT.
The subwoofer emits a quiet pop about every 2 minutes.
No driver assist beeping when objects are close.
no backup camera obviously.
Instrument cluster says "EMERGENCY CALL SYSTEM MALFUNCTION" - but the emergency call system functions fine, I talked to them.

I am not a rookie. I have installed many, many amps, stereos, speakers, etc. At no time did anything short out. Any help, ideas are appreciated.

I am hoping it's a fuse......

[capese21]

Have you flattened the battery(s) during the install? I did similar once. A low battery will cause all sorts of odd electrical issues.

[DanGPrice]

Update to initial symptoms: It turns out that I CAN CONNECT with BimmerCode. Bimmercode does it's initial reading and the HEAD UNIT is no longer displayed. Also, in the HUD, the Speedlimit sign now shows LIMIT no matter where I go. So it's not getting the information it expects. So I am thinking a fried head unit module or still, hopefully a fuse.