Odd Macbook pro Issue

I will try and make this short as I can

I have a 13 inch Macbook Pro 2010 model

1. If I start it up with no Hard Drive and nothing in the disc drive it stays on with the ? folder flashing

2. With the Hard Drive in it starts up but unless I press ANY key on the keyboard it will shut down during start-up like I was holding the power button down. Once booted up, if I let go of the key or don't press a key for about 10 seconds the power menu auto pops up like I pressed the power button and if I don't press a keyboard key it will shut down a few seconds later like I was holding down the power button.

3. If I use the install DVD it does the same thing as stated in number 2

4. If I use an external USB Hard Drive loaded with the install disc it actually gives me a kernel panic. Same as if I use the Hard Drive with an external adapter it gives a kernel panic.

5. If I start the computer without the keyboard the computer stays on fine.

I know this makes it sound like a keyboard issue but if you refer to number 1 where the computer can stay on indefinitely with the ? folder flashing that shows its not a keyboard/power button failure, seems something else

Anyone have advise?

I do not have warranty left on the Macbook, tried PRAM, SMC and all other resets

I would guess it's a bad power button. That would mean a replacement of the housing assembly. I understand what you're saying about #1, but if the button is permanently depressed, the unit might not receive another signal to shut down if the system doesn't receive some sort of interrupt.

The part cost for the upper case assembly from iFixit is about $300. If you were going to spend that much, I'd recommend having Apple do the work for their flat rate repair program - between $285-320 depending on model. That's of course if there's no physical damage to the unit and no liquid spill. Once those factors are added, the cost goes up dramatically.