Responsive only to power refresh when locked up.
The unit is located remotely in a shed, connected to the network through an Edimax EW-7303HPn V2 Wifi bridge to my Wifi router. The Router signal level is fairly weak at the bridge but the bridge and a Wemo switch operating through the bridge are reliable. I use the Wemo switch to reset the sprinkler unit when it locks up.
The sprinkler unit operated reliably when connected directly to the router driving only LEDs during the testing phase pre-installation.
So it seems that the sprinkler unit cannot cope with a slightly marginal Internet connection.