Thanks @hyphop, I already have tried this. I can flash any image with kernel 4.9 and old u-boot and it works fine, even via type-c, kresque image or kresque usb drive. When I erase emmc and write a 5.7-based image with a new u-boot, I have tried all available ways of erasing emmc and flashed the new image both via emmc-install and via kresque usb export. All tries ended up with booting into new u-boot with “no partition table found” message.