I would take everything out and build the pc outside the case with the minimum components connected to get it running.
Put Motherboard on non conductive area, some people use the motherboard box, dont put it on top of the antistatic bag.
Reseat cpu and heatsink.
Reseat ram, if you have 2 sticks just install 1
Reseat power cables, dont install anything else.
Connect display to motherboard, dont install the gfx card
Clear cmos (shows how in manual chapter 1.6 jumpers )
To power on without the case some people short pins with a screwdriver however to be safe I would buy a cable to do this, you can search for HDE ® Power Sw Motherboard Cable For Pc Power Switch Button
Basically connect the minimum amount to see if the board will fire up.
On other forums with different Asus boards some folk that had the blinking led were caused by dodgy psu or faulty front panel usb on case.