First steps were to trouble shoot what was actually wrong with the unit. Prior to stopping working after applying power the unit would turn on all the LEDs and then the progress bar would light fully before rapidly reducing to zero. It was no longer doing anything on power up.

After removing the case and checking for anything obvious eg anything burnt etc. The first thing I noticed was like any appliance in Sydney (and I'd assume many parts of the world) if it's warm and contains food, it will have signs of cockroaches and this was no exception. However it did seem confined to the crumb trays and the high voltage side. Judging by the few dead roaches they likely didn't survive the toasting cycle. Nothing however, looks to have obviously failed.

All the internal wiring is high temp fibreglass braided, there is a small transformer that leads to the mainboard along with a number of daughter boards. These a broken up into the main-board that includes the low voltage power supply, a micro and the toast level control, a input/LED board (buttons with lighting), a LED progress bar board and finally a relay board for switching high voltage components.

A quick test with a multimeter shows that the transformer is good and is putting out ~13V AC. Following "thou shalt check voltages" the AC input is rectified with the raw DC being supplied to the relay board as well as a 5V regulator providing power to the micro. Both of these voltages are present and stable. I also at this point wire up an alternate AC input plug that I can plug into my bench-top AC supply to more safely power the main board.

After testing various points and giving the unit a good clean it is looking very much like the micro is not working. This rules out a "simple" repair.