Try boot without any ram installed, do you get error beeps / or flashing lights?
Use this video for disassembly but dont use metal tools like that guy, something plastic or just your hands (you can have ram on if you tested it all ways and it wont work):
https
/www.youtube.com/watch?v=o23ZvfIn3aI
If fan starts spinning you found the short and its the part you just removed before trying to boot, if your familiar with tech you can go on with disassembly after my advices but if not i can help what to do after this. Always after you try to boot use only power cable and if it failed take it out and press again 10sec power button and continue with disassembly
1. always remove battery and power cord before disassembly and press power button for 10seconds to drain any current from the motherboard
2. after removing front panel at 7min0sec you see cmos / bios battery round one with 3v, remove it and press power button (you see power button connector and button so you can press it even without front panel) for 30secs. If dont work buy new cr2032 battery for it or remove it and try to boot. Try it all ways.
3. at 7:20 you see him remove usb board connector do that and also 8.45 he remove wifi card, remove that too. After removing connectors try to boot. ( be careful not to leave any connectors hanging around and shorting motherboard)
4. 7.50sec he will remove screen connector, do that carefully and try to boot, does fan start spinning?