What to do if I get a"Bluetooth is off" error while pairing my KardiaMobile 6L.

This screen will show if bluetooth is not on during pairing. Bluetooth is required 

Android

1. Tap the "Go to Settings" button on the error screen
2. When in the settings, tap the "Permissions" area to trigger the prompt to turn on bluetooth
3. choose "Allow"

iOS

1. Swipe open your iOS control center by swipping up from the bottom edge of any screen. On iPhone X or later or iPad with iOS 12 or later, swipe down from the upper-right corner of the screen. (See here for more information about your control center). The control center will display a series of icons.
2. Tap the "ᛒ" icon to turn it blue. This turns on your Bluetooth.
   
3. Return to the Kardia app
4. ap "Retry" on the bluetooth error screen

Or...

1. Leave the Kardia app, and go to your home screen by pressing your home button (or swiping up if using an iPhone X or newer device with no home button)
2. Open your Settings application 
3. Choose "Bluetooth"
4. Toggle ON the toggle for bluetooth by moving it to the right, so it shows green:
   
5. Return to the Kardia app
6. Tap "Retry" on the bluetooth error screen

You're all set, and the screen should transition to the normal recording screen.