Modifying the mkrzero bootloader to have differ usb ids

Hi,

I'm trying to flash a custom bootloader onto a samd21 chip. I've modified the usb pid and vids in both the boards.txt file and in the samd bootloader found on Arduino's github GitHub - arduino/ArduinoCore-samd: Arduino Core for SAMD21 CPU.

In the windows device manager it still shows up as a mkrzero and the usb ids don't match the ids I set in the bootloader.

I'm not sure where, but it's clear I'm missing something. I'm sure I flashed the bootloader I've built onto the chip, and not the stock arduino bootloader.

It's clear I'm missing something, but I can't find out where.

Any help would be greatly appreciated.