Switch off psu, unplug it from wall, remove shiny battery from motherboard,switch psu on (without plugging into wall), press and hold power button for 30s~, plug back battery, switch psu off then plug it into wall and then switch it on.
If it doesnt work, unplug gpu, hdd, leave 1 ram stick, and unplug rest of peripherials except monitor.
Plug monitor into motherboard and start up pc and see if it works, if it doesnt try another ram, or ram slot.
If it still doesnt work I can assume that your old psu has taken your motherboard with it.
Just an question where do you live?(just point out country)
Cause the psu is high quality but I dont say there are any lemons.