I haven't connected any HDD yet just trying to get something on the screen (bios screen).
The GPU fan is like running at full speed which never happened before.
List the parts please.
Have you plugged the additional 4/8pin ATX in near the CPU socket?
Take the GPU out and try the onboard solution?
Try one RAM stick at a time in different slots.
Turn the power off and pull the battery out, go make some tea, refit and try again.
You need at least a single RAM, board, CPU+cooler to get to POST.
Cant be in a worse position than you in now.
Just use it enough to see if you get a POST screen.