Well I was trying to setup my LEDs I haven't touched since I put together the build a couple years ago and I had a couple wires that would connect then fan LEDs to the psu and when I connected them and turned them on i noticed they worked but I heard a popping noise and I got scared and shut it off from psu switch then I removed the wiring and turned back on to no display on the screen. I have tried another graphics card with no luck. I have no idea what it could be.
More aboutburn smell computer
What smells burned? Does anything look burned? If you had a burn smell it should be pretty easy to track down, something obviously died.
Well for the display remove the cmos and put it back after 30 sec and it should work where as the burning smell would might be from leds.