Electronic gremlins, need help troubleshooting...

[Snowman]

2days ago i recieved a cruise control retrofit kit, i fitted the new stalk and all the wiring except the cable to the engine bay since i didnt have time at that moment.
The car worked as previous after fitting this kit.
Today i went on to remove the ECU and grind away the "cage" around the ECU connector and i was also fiddling around behind the dash, above the pedals in the cabin to try and find the rubbet grommet which i should pass through the last cable for the cruise control retrofit.
But without success, so i bolted everything together again and now i seem to have caused a few problems..

The following things do NOT work:
-Brake lights
-Indicator stalk do not work in any direction, no clicking and no indicators turns on
-Interior light is ON in all times, no matter if the door is open or not. If i put it to the "off" position it turns off, but when its supposed to turn on when a door opens its lit all the time.

Indicators work fine when i turn on the hazards.
I get a fault code on brake light switch, implausible signal when i try to brake.

Any ideas on what i might have messed up? Any pointers to where i should start looking would be appreciated..

Worth mentioning is that i have no codes except the code for brake light switch. It pops up after braking.

 

[Snowman]

Could the actual bcm be damaged and cause these problems?

 

[RUM4MO]

Sorry but I don't think that me guessing here is a good plan, at worst it could lead to you buying a new BCM and ending up with the same issues.

I'd be checking and rechecking the new wiring harness and making sure that everything is plugged in correctly, or fully and that includes checking that there are now no bent over connector pins.

After carrying out the above checks, I'd try reversing all the wiring changes to make sure that everything now works okay, you might need to carry out a full "all smart controllers" scan and clear all logged faults as well.