Won't boot past the KDE splash screen

[mouffa]

indeed, if it turns off it's strange, it seems something crashes hard, later came an update of the Qt package and maybe it solves your problem but if the phone turns off you will have to either do the chroot or reinstall the image, another way could be to alter the files and stop Plasma from loading automatically until you do the update but it is easier to reinstall the image, try the updated image with the SD and if it's OK flash it to the eMMC