Add new MCU SAME51N19A

Hi,
I am hoping someone can help me. I originally was using the Adafruit GrandCentral board which uses the SAMD51P20A MCU chip. As many of you know their is a shortage of MCU's and I cannot get any of these MCU's. The only MCU that I could purchase was SAME51N19A. Here is what I have done:

  1. Upload grandcentral bootloader into the new mcu. (bootloader area is write protected)
  2. In the boards.txt file edited the grandcentral m4 for the new mcu (memory size, etc)
  3. Modified the variant files for the new mcu pinouts.

When I compile using arduino IDE and download the simple led blink file to the new mcu the download seemed ok but program does not run - then it looses the port and the bootloader is bricked.

Not sure what I am missing. Any help or guidance would be greatly appreciated.

@Jimbee
Re your request to close the topic: I request you give us the solution you found so that others may learn from what you did.

Thanks,