yea I'm stumped as to why nothing is appearing on the monitor.
it would be so much easier if you had a "motherboard speaker" to attach as you could be missing error code beeps from your motherboard that could help us determine exactly what is wrong
they are about £1.50
even me new £120 case didn't come with one , my sons £70 case did not have one either.
there was a time when the speaker was build into the motherboard itself and then a time when every case seemed to come with one.
since high end motherboards have a little LED number display it seems they are never included any more and they must only cost 10 pence to manufacture if you were a motherboard/case manufacturer getting them in bulk.
you are so unlucky to have a pc build that doesn't just work out of the box though , I've been building computers for over 10 years and never had a problem so far.
don't let one hiccup put you off building your own again in the future.
the only thing I could think of is there seems to be a wire with a connection coming directly from where the hdmi port is on the motherboard , try removing it and then reinserting it?
Never seen a hdmi port build into a mobo like that before tbh. (EDIT: never mind it's apparently just the cmos battery being completely different to how they normally are)
also if you didn't already try the hdmi port on your tv you should, I think you said you were trying the vga port with your monitor.