This started off by losing pressure after warming up and pulling the first shot. All the way down to zero and then never turning back on and eventually cooling down. It was still able to warm up and build some pressure after turning off and then on. Now it's not able to reach the temp/pressure from a cold start, but it's doing some boiling, but then it doesn't.

I noticed some subtle hissing going on, both while it unsuccessfully tries to warm up and when cooling down from the first shot. Is it possible that opv is stuck open due to some scale? It's a 2yo warranty unit, but doing UPS/USPS chores seem like more trouble if it's a matter of tweaking opv a bit. Thanks.

Edit: looked at the diagram which says OPV is something in between the water pump and the boiler (?). I had problems before with La Pavoni where the valve is sticking out of the boiler. Whatever it is here, it seems to be hissing and the pressure gauge eventually (like a minute after it starts) shows zero.

Not OPV. That wouldn't prevent it from heating.

Sounds to me like your powerboard (Inside the electronics box) is dying. After it heats up, the transformer on the powerboard fails and either the logic board no longer senses the water-level sensor (So it stops heating) or the transformer's output is so low it can't operate the powerboard's own relays and it can't turn on the element. If you're lucky, it's just the relay on the powerboard that's burnt out, because it's cheaper to replace.

If it's the relay, and it's the relay because it's wired in the old way of using the powerboard as the load switch for the element, you may consider installing a solid state relay or some cheap sacrificial relay external to the powerboard to take the abuse. Or simply wiring it to use the p-stat itself as the load switch, the little Ma-Ter Pstats are much cheaper than powerboards. The little microswitch alone is even cheaper. Much cheaper in the long run.

If you can get a replacement board and swap it out you'll be able to prove that that was the problem and you'll have the spare board to consider soldering a new relay or transformer on to.

TY. Makes sense that OPV hissing it would keep heating, it was just suspicious that it puffed something while pressure already low.

Another data point I forgot to mention: first the no-water sensor started blinking while there's plenty water. I jiggled the water tank to solve that and the real problem started within a couple of weeks, I think... It's not blinking now though, just stopping heating. If that sensor is the problem, not heating makes sense, but not blinking doesn't. May be I should get rid of water and see how that goes with the sensor;-)

I'm 2yo and still on warranty, so I'd rather ship it to Seattle than try anything myself to do with the powerboard.

And you're certain that the boiler pressure is ACTUALLY zero, right, Not just cold?
It's not a case of it "Boiler Filling" with the breather valve (Antivacuum) stuck closed? If you open the steam wand it doesn't begin heating up?

Yes, tried that, no steam coming out. It's actually quite hot, cooling down takes time, losing pressure takes like a minute. So the boiler is de-pressurized somehow.

Removed all water from the tank and it doesn't want to blink asking for water, just starts boiling. I'm a little afraid of it now...

As I think you should be. A properly working controller that fails to sense reservoir water will blink and will not power the autofill solenoid/pump, nor the heater. That's a safety feature.

If it's not blinking but still somehow powering the heating element I think you probably have a controller problem. These aren't cheap and your best bet is to try to get a fix under warranty. They might ask you some questions and arrange to ship you a new controller that you can replace yourself, but more likely (and probably best) to send the machine back so they can diagnose the whole thing.

Modifying the heater circuit so as to avoid frequent high current switching by that controller relay, as JRising mentioned, may be a good idea -- many of us did that on old Rockets and ECMs that had a similar electrical design. But it's probably best to save that for after your machine is out of warranty and you're up for a little electrical rewire adventure.