A power surge will wreak havoc on any eletronic device.
One item you may have missed is the four or eight pin CPU connection from the PS to the MB near the processor socket. The processor could be fried also.
First, did you do the PS, MB, and HDD replacement by yourself? What about other components such as the memory, graphics card, or any other PCIe add-on devices you may have? How about the USB card reader?
The surge could have fried everything connected to the motherboard up to keyboard, mouse, the power switch and front LED's.
You could still have a bad component or you may have not connected something correctly. Check all connections on the MB to the new PS. It is also possible the new MB is faulty.
Hey Grzy, thank you so much for your response. I did do the psu, mb, & hdd myself and after reading your comments I think I'll take the computer to a real professional repair & have them look at it. Your comments are much appreciated, hapsquires