So, I removed my emmc .
Then I installed both the latest Testing version : 20200118 & the stable petitboot (20191127).
Neither do turn on my screen (Pioneer PDP-507xa) in SPI mode, which got me worried enough to use:
petitboot Recovery Image (20190417) (see the first sentence in this post).
Which fixed things, and then I installed the stable latest petitboot again.
Once more I could run the latest CE nightly from a uSD, although still blind as a bat in SPI mode.
I started to look for a solution for the “flying blind” situation and stumbled upon this.
I installed my emmc, booted CE from my uSD, enabled ssh, and proceeded by coping the latest CE nightly with winSCP to the ‘/var/media/STORAGE/.update’.
Behold, it apparently flashed the emmc, since I have my old system again with the latest nightly CE.
Have not yet found any solution to the bats bashing into the plasma tv situation, sweeping up those buggers is a chore, which would be nice to have fixed. The mentioned usb mass storage mode could very well save my precious N2, although unlikely, if the need would arise.
Although, it mentions to alter the: kernel parameter ‘disable_uhs=<true|false>’? How does one unlock this achievement, being blind?