ok. avr.... yep. that's what it's going to be. and it's fine. just have a small window to catch it.
this might help catch it, it's the way i do it. (copy/pasted from my response on another thread)
- promicros can be tricky to flash, even with resetting twice in a row you only get 8 seconds to catch the bootloader
so, - edit & download the firmware
- open QMK toolbox and get it ready, select the correct firmware
- reset it twice quickly
- as soon as you see the port open up in the window, click flash.
- wait for the confirmation message that flashing was successful
other notes: used VIA and keymap you just flashed is not the keymap the board is using?, try clearing the EEPROM.
- reset twice quickly
- soon as the port is found click "Clear EEPROM"
(i've run into this myself with flashing new firmware while there was a previous keymap sitting in the EEPROM from VIA, so my revised keymap in the firmware was being overridden by the keymap in the EEPROM from VIA.)