First to Check: when meet "???????????? no permissions" by using adb devices

If you meet following problem when using adb devices in Ubuntu

~$ adb devices
List of devices attached 
???????????? no permissions

Try this first:

sudo killall adb

sudo <adb-dir>/platform-tools/adb start-server

Then:

sudo adb devices

* daemon not running. starting it now on port 5037 *

* daemon started successfully *

List of devices attached 

HT24LW310170 device

The reason for this problem is that adb need root privilege to start server.

If "sodo adb" generate error "sudo: abd: command not found", you can try this:

sudo -s
adb kill-server
adb start-server
adb devices

Or you can cp adb to the user/bin:

sudo cp <adb-dir>/platform-tools/adb /usr/bin
sudo chmod +x /usr/bin/adb