Multiple Device Flash / Resellers / Company
Follow each step in order.
Only press Run Security Install when every device shows Connected.
adb kill-server (see below), then press Connect a Phone via USB again. This doesn't disconnect phones already connected on this page.adb kill-server: close Android Studio and any phone apps. Open Command Prompt (Terminal on Mac/Linux), cd to the folder where Android SDK Platform-Tools is installed, and run adb kill-server. If you don't have Platform-Tools installed, closing those apps is enough.ADB or Android tools on this computer
If you have any ADB or Android tools on this PC, they may cause "Allow USB debugging?" to pop up when you connect devices.
adb kill-server, then do the process mentioned above. You may need to do this a few times to get all your devices connected.One license key per device. Press Validate on each. Only validated keys can connect a phone.
If you do not have a flashing license, click here to buy one.