I first emailed them 11 days ago now, if emailed again giving my Gmail address in case they were having problems with my normal address.

I wish I could do some troubleshooting to find out which component is at fault (PSU, power brick or motherboard). The obvious thing would be to plug at normal ATX power supply in, unfortunately all my ATX era PCs here are Dells, which means the ATX connector isn't really an ATX connector. I might have to go and buy a real ATX PSU just to test this.