Not sure if the same symptom as you. For me, it powers up, but will never go solid light (ie. at temp). If I press a button to make coffee before it is at temp it will flash the light for that size, but after a while instead of making coffee it flashes both lights quickly and locks the machine.
Unplugging it and plugging it back in solves it instantly every time and lets me make coffee, but every morning I have to go through this process. Thinking about plugging it into a mini powerbar with a switch on it, so I can quickly power cycle it.
My hunch as an electronics technician, though I've never taken it apart to test my theory, is that the thermal compound for the temperature probe has gone bad, causing the reading to lag the heat, resulting in an overheat situation, which the internal logic eventually detects and locks the machine out. Hence why powercycling fixes it and results in normal espresso.