Some uaefi boards (BAD BOARD) seem to not initialize 5VP regulator (GPIO::E10) when voltage is below 11.4 (ish, we ran some tests on one example board). This leads to a NO START condition. If board is connected to USB, 5VP initializes and everything is fine, even below no start threshold voltage. and power keeps on.

Other board examples (GOOD BOARD) will boot down to 6-7v input voltage just fine.

When this board (BAD BOARD) is powered below booting threshold, DFU mode still works, so MCU is alive and powered.

Same board loaded with 407-disco firmware initializes just fine (which is odd, cause GPIO::E10 is something totally not power enable, it's assigned to something in the stepper territory, so may be it just so happens to work.

Anyway, please make UAEFI initialize 5VP more reliably.