I installed a BLTouch on my Ender 3 following this video: https://www.youtube.com/watch?v=sUlqrSq6LeY.
What I noticed too late was that when installing the BLTouch, I swapped the brown and red wires followed by connecting it to the mainboard.
Then I realized that the printer wouldn't turn on. After reading some of the comments, I swapped back the wire and I could see the BLTouch do its self-test.
However, it seems that I need to plug into the USB before the LCD + motors can work.
So is my mainboard fried? Or how should I fix it?