My Breville / Sage dual boiler doesn't want to power up, with the power light on and the steam light to the lower right of pressure gauge is flashing. I've moved the lever up and down, played with hot water knob, emptied / filled water tank all to no effect. It pulled shots fine this morning. Had a search around and could only find recommendations to send back under warranty. Any advice on how I can diagnose and address this issue?

Unsure if relevant: after a week or two if ignoring the "clean me" light I got around to buying some cleaning tabs and descaled it for good measure. After I'd bought descaling goodies I realized that unlike the BES920XL the BES900XL doesn't have a descaling function as there are no ports to access it. As my water source is particularly hard and I bought this used from FB marketplace so it's at least a few years old and I figured I may as well go ahead with this solution, which took a while but removed a scary amount of gunk from the steamer tank. The other tank was repeatedly flushed of descaling solution by running the water reservoir empty and refilling with normal water and a few shots were pulled and discarded for good measure.

I also had a few issues with the triac board and I orings which I previously asked about. The leaking probes somehow resolved themselves after a few weeks of being ignored. I thought water impurities may have sealed the leak but the water would only reach the probe as pure steam... weird.