If a Mains voltage device, like your coffee machine, stops working. Don’t just throw it away, check your frequency on your inverter.
Many of these appliances use the frequency to run electronic circuitry and this fails as the frequency drops.
The next thing, not to panic about is that your inverter might have given up the ghost…. because to any reasonable voltage drop going into it will see your frequency drop coming out.
Another Kiwi boat just recently went out and bought a second coffee machine after his failed, which also wouldn’t work, then after having a chat with us, and of course a decent coffee, he went through his 12V connections (which were all beautifully made BTW) and found some that needed a little tightening. Suddeningly he had back both a full 50hz and two working coffee machines.