I agree that it takes a lot of knowledge and practice, not sure if you want to learn a ton of stull just to fix one psu
for starters get incandescent bulbs, 100W 220v(or bigger) one to connect supply thru the bulb - this way you wont fry it if you make a mistake and short something, and a bunch of 20W 12V ones to load voltage rails
is powergood present? does it try to start?
usually you start from the wall socket, identify pfc controller and check if it works, identify main smps controller, check if its powered, check if it starts etc
edit: typo