I've been working on an ATmega32U4-based PCB for a custom keyboard for a while now. I made a few prototypes with similar designs, but they all seemed to have issues with the microcontrollers dying after a short while of use.
The symptoms are that the board works perfectly fine for a few minutes after first connected but then disconnects according to Windows. Unplugging and replugging the board results in another few Windows connect and disconnect sounds but with no response from the board. None of the keys I am activating are making it to the computer and hitting reset to put the controller into bootloader also results in no response.
I've included a few screenshots of the schematic and board layout below as well as a Google drive link with the BOM and the Kicad design files.
Any help would be greatly appreciated as this has been frustrating me for months now.
Note: I have changed one thing since my last prototype and the design files that I attached here. I had a trace crossing the traces going to the crystal on the top side of the board which I was advised could cause some interference. I changed that trace (labeled COL5) to now avoid crossing anything crystal related even if on the opposite side of the board.