Hi there sorry to here about your problems, the first thing I'd check is the main power switch. This switch works independent of the syil electronics, it is controlled via a small relay. This relay is built in to the switch, I have seen them fail before. In one case, I seen the small spring on the relay come off and once this spring was re attached it worked.
Other then that I would check it with a volt meter, it sounds like the main switch needs to be replaced.
Any questions let me know,