It's working again.
powered off, removed battery, and left overnight. Powered up and blue light started flashing. Flashed again from the web and it's working OK.

I flashed a new unit (LilyGo LoRa32 with Meshtastic) and everything worked OK. I changed some settings from the dashboard, saved them, and everything worked OK. (Board rebooted as expected)
I decided to change some of the settings back to the initial values. When I tried to save them, the board started rebooting and stayed on that screen for over 5 minutes. I powered off the board and when I tried to turn it back on, the screen stayed black and the red LED stayed bright.
I tried to re-flash the board but it won't communicate. I can see it in the device list and on the connect screen. When I try to connect, there's no response.
Is there a way to hard reset the board?