Hello guys, new to the forum here.
A bit of backstory:
I have owned the clk55 amg 2004 for a couple of years and had a lot of fun with it, rebuilt the engine last year due to a faulty oil suction tube o-ring.
then in the end of september i took the car to a trackday where it caught fire due to the rubber hose from the power steering fluid cooler popped of and pissed oil all over the manifold, i put the fire out within 40sec with the original powder device that came with the car.

The wireing for the o2 sensors, oil level sensor, crank position sensor and the intake valve got fried pretty bad, at the time i was in the prosess of moving so i decided to just give it a very thurogh wash to get absolutely all the powder away due to it beeing corrosive asf, and then left the car for a month, when i came back to work on it i noticed that mice had got in through the fuse box and the ac blower motor.

I then decided to start with the fire damage and solidered up all the wireing and fired it up, all is well with the engine but i have a fault code for passenger side o2 sensor before katalysator. I have swapped out the sensor so i know thats not the issiue, and i have checked for cotinuety in all the wires coming from the contact (i checked with the fault code reader aswell and it does not get any signal from the sensor)

i then cheked the obd scanner again and now it is only getting a signal from the ecu and the tcu, before it was able to read abs, esp, airbag, overhead controls, instrument cluster etc.
i then ripped apart the fuse box to find the mice had bitten over 3 wires so i soldered them back up again but thus did not fix the issiue. Sometimes if i am lucky i can read out codes for the rest of the systems but its far apart,
can it be a bad ecu due to the fire? does anyone have any idea why i cannot connect to the remaining systems? And why does the ecu not get any readings from the o2 sensor

sorry for the long text but i am completely lost here.