I have a R58 V2 bought new six years ago.. recently sometimes when the pump turns on (either making an espresso or just turning on the hot water tap) it at some point (sometimes right away sometimes halfway through) turns off and the green light blinks once. Sometimes it works OK. The water is plumbed in and the only thing I can google is that it has to do with the reservoir sensor which doesn't apply in this case.

Plugging in the screen, it shows "Water Filling" when it is filling successfully.
When the light blinks it changes from "Water Filling" to the startup screen that shows the version number, like the power was reset.

The only thing I can think to check is disconnecting the water line and checking flow but considering it sometimes completely fills and other times shuts off right away I don't think that's it.

Update: Works fine using the reservoir I'm thinking the solenoid for the plumbed in water is crudded up and only working sometimes. Is that common? I might order one there is three in the machine probably will need one sooner or later.