MCU hax can and will brick if you fuck up.
From my understanding, the SoC (CPU, GSPGPU, etc) is still able to init with a busted MCU, and the MCU isn't in between the CPU, Bootrom, or NAND, so it will continue to load an a9lh payload from the SD card.
afaik, PMIC (The power management chip, which has no user-serviceable firmware) handles the power button before MCU does. This is likely due to a factory preinstall condition.
You can probably hotwire the PMIC or SoC to power-up the system, too.
What this means, is that using I2C commands from arm9loaderhax, you can reflash a clean MCU firmware, and then when you power-cycle the machine, it should be working.
The screen (at least, the backlight) will not be able to initialize until the MCU is fixed, however.
Last edited by sirocyl,