Android N Beta update failed, how can I try again? I enrolled in the beta program.  OTA update appeared, downloaded, unpacked and restarted. Then it loaded up a great little "ERROR" screen with a sick looking Android :/

After restart, it booted back up in Marshmallow.

OK, so no big loss, just time. Happy to try again...but I can't find a way to force the OTA to reappear?
Turns out it just took time. By the next morning I had another alert asking me to download and install the beta. Despite having checked for updates and restarted the phone to see if I could trigger it.