Hi,
First start with another hard reset, disconnect the power cable from your PC and press and hold the power button for 20 seconds. Plug it back in and see if the PC will boot up normally. Next is to reseat the RAMs, remove them off the PC for couple of seconds put them back in and see if it will make you PC boot up normally. Lastly, if you have a dedicated graphics card remove it, connect your monitor to the on-board graphics card and see if it will display anything from it. Also do try another monitor and see if you'll get any display from it.