内核启动顺序错误, 启动了旧版内核, 建议修改文档不是单纯的安装新版内核, 还要卸载或修改旧版内核的启动顺序。
一种会导致无法识别 /dev/mtd* 的可能。建议修改一下官方文档
After installation, check file /boot/extlinux/extlinux.conf. It lists all kernel version installed in ROCK Pi. The kernel corresponding to the first label is the newest version and the first boot option.