Burning Bootloader for m32u4 via ISP

Hi guys,
just bought myself an Arduino Micro!

So this is the story:

First Sketch, super exited
Program Blink on PIN 0
Works Fine
Realise I overwrote part of the serial communication
Cant upload sketches with USB anymore (how stupid can one be :o)
Use Raspberry to clean up via ISP / avrdude

The programming with AVR works just fine, but I couldnt find any firmware
or bootloader that made my Micro communicate serial again and work with
the IDE. I’ve tried ATMega_168.hex, some firmware for the Leonardo and a
manually compiled version of ATMega_168.c. Nothing worked.

Please Help

The ATmega168 code certainly won't work - as the chip on the Micro is a 32u4 not a 168.

The bootloader you want, per boards.txt, is caterina/Caterina-Micro.hex

micro has two serials, pin 0 is for Serial1. Micro dosen’t use Serial1 for uploading codes.
-Malhar