I hope this explains a what/why on what ''may'' have occurred. My recommendation is, if it's no longer playing up, leave it.
A rare occurrence with breville coffee machines is having the water pump flow when it shouldn't. The worst scenario I have heard about (from a tech, but not me) was one that would turn itself on, run the pump until all the water was gone. It's very uncommon, I only know about it affecting Breville. Breville is also marketed as Kambrook, Ronson, and in the UK 'SAGE'. What you're describing sounds like this, but impossible to say for sure. For the record, I love breville coffee machines, i've owned 4.
The issue is with a leaky electrolytic capacitor in the power supply board, combined with the soft-start standby mode. Replacing that caps corrects the issue.
That was 11 years ago for me, wow. Here is a post I added to about it. https://siber-sonic.com/appliance/800Electrical.html#nopower