I believe I might be having similar issues.
I received the OSPI v 1.2 board a few days ago and was running perfectly for a day and a half, since then every few minutes it seems the OSPi is rebooting as I can see it connecting / disconnecting constantly on my switch. The power supply has now been swapped (removed the power connectors from the sprinker board and replaced it with the usb power). It has only been an hour or so now, but it hasn’t dropped out since.
Is there any test I can do (apart from trial and error) to find out that it is 100% the sprinkler board playing up?
Also I don’t believe I received the screws / board lifters in my kit originally.