Remove the CMOS battery, go and make a coffee and drink it, take your time to let the CMOS drain. Replace the battery and try again. If it works you're lucky, if not your BIOS chip may be toast. Is it surface mount or sitting in a holder? If the latter, make sure it's pushed home tight.
I've got an HP ML370 G4 which powers on, the fans spin up and... nothing, no splash screen, Nix! I've removed memory, etc, and reconfigured it to a minimum system (removed all PCI cards, etc, and still nowt.) In my case, I'm 99% sure the System board is fried.
Like H TexMex H says, "any beep codes" which would indicate the BIOS still lived. Removing memory, leaving the minimum, normally forces the BIOS to display a message to let you know the config has changed. (Nope! None of that worked with my box.) >sigh<
Be lucky & Play Bonny!