前提：USB调试都打开了。USB连接方式：MTP。$ lsusb 能看到你的设备。
1，先尝试换一根好一点的usb线
2，还是不行？尝试尝试这些帖子的解决方法：
https://askubuntu.com/questions/632651/adb-devices-command-wont-detect-my-4-4-android-phone
https://stackoverflow.com/questions/15721778/adb-no-devices-found
反正我是按照2折腾半天，没想到回过头换根线就好了。。醉
注：
adb调试平台下载：https://developer.android.com/studio/releases/platform-tools
unlock教程：https://club.huawei.com/thread-4790911-1-1.html
1, install TWRP:https://twrp.me/huawei/huaweihonor4x.html
2, install Magisk：(How to Install Magisk Latest Version 20.4 on Android [Non-Rooted Phones]) :
3, How can I root a Huawei Honor 4X?
工具：
9008强刷
https://www.youtube.com/watch?v=W8salW6m-z8
https://www.shangmayuan.com/a/980fe373230543409536fafd.html
1，dc-unlocker需要破解
2，octoplus: https://www.youtube.com/watch?v=GeMC_ZtxE98
https://octoplusbox.com/en/download/software/
3, XDA https://forum.xda-developers.com/honor-play/how-to/unlock-bootloader-unofficial-free-t3914658
https://www.muzisoft.com/rom/179960.html
https://nizaina.lanzous.com/b00nb544d