Concept 2’s PM5 Firmware Overview page has a good description of how to update your firmware.
Here’s how to test to see if your firmware is a version that is compatible with the HereNow VR app:
1. Create a HereNow account if you haven’t already. You can do so at the address https://herenow.com
2. Download the HereNow VR app from the app store if you haven’t already.
3. Open the app on your phone and log into it with the HereNow account
4. Go to “Practice as a Rower”
5. Click “Connect to Erg”
6. On the erg, go to “More Options” -> “Turn Wireless On” to enable the bluetooth connection. The erg should appear in the app with a red “Connect” button.
7. Click the connect button in the HereNow app to connect to the erg
8. Go back to the settings screen
9. Pull on the erg handle hard enough for the erg to register the speed.
-> If the HereNow app shows the data changing, then it is connected and the firmware is fine.