I'm not certain of the proper terms, but in the wiki they do discuss part of the pre-boot directions are on the eMMC module.
So a corrupt eMMC can cause it to not boot from the SD card also.
I have been 'playing' with Linux for 30+ years, but I am not tech savvy even yet.
There are tech methods to fix the eMMC, but I would simply remove the eMMC module, and use the eMMC to USB adapter to correct this.
Then re-install the module.
The keyboard is isolated from the operating system,
so unless you changed the keyboard firmware ? It should not affect keyboard performance.
So a corrupt eMMC can cause it to not boot from the SD card also.
I have been 'playing' with Linux for 30+ years, but I am not tech savvy even yet.
There are tech methods to fix the eMMC, but I would simply remove the eMMC module, and use the eMMC to USB adapter to correct this.
Then re-install the module.
The keyboard is isolated from the operating system,
so unless you changed the keyboard firmware ? It should not affect keyboard performance.