Hi RB, welcome to NST.
First thing to find out - Is your Mobo communicating with the HDD ?
In the BIOS, can you see your HDD listed ?
With the PC powered off, (but with the power lead left connected to maintain the chassis earth path) try disconnecting all the HDD leads and plugging them in again several times.
This will clean up any tarnished pins on the connectors.
I've cured dead systems in the past with no more effort.