After messing with eMMC partitions, PBP won't boot, even from SD card

[granstr0m]

Messing with the partition layout is a bit dangerous, because the start of the eMMC/SD card is layed out in a specific way. 

The RK3399 SoC will read it's idbloader.img from byte 32768 (from the start of the device, sector 0x40). 
After that is the u-boot at the magic offset byte 8388608 (sector 0x4000). 
That's the reason why partitions are starting rather far into the device on the stock images, to make space for the bootloader and SPL.

You can find more information about the boot process in this wiki article from Rockchip:
http://opensource.rock-chips.com/wiki_Boot_option

In short: Don't touch the first ~16-32 MiB of the device and you'll be fine. 
Otherwise, you'll need to dd the bootloader and idbloader back onto the partition after your actions: 

Code:

dd if=idbloader.img of=/dev/sdb seek=64
dd if=u-boot.itb of=/dev/sdb seek=16384

(as root, these files are probably in /boot)

Tobias

Ooops, I just did a dd if=kali-linux-2020.2.x.x.x of=/dev/mmcblk2 yesterday

Very strange that it worked on the first reboo until today when I rebooted again and it just stays with the orange led.  

So how are you supposed to flash let's say Kali to the eMMC???

dd if=kali-linux-2020.2.x.x.x of=/dev/mmcblk2 seek=32768

Would that work??? If I first manage to restore the boot and idbloader, that is!!!