Alienware m15x Laptop, no longer boots up after graphics card replacement

So my laptop's graphics card died just before Xmas, warranty is long gone now so ended up taking it to a tech. Originally my laptop had a Nvidia GTX 260M, the tech was able to get ahold of some 460Ms instead. From what I understand the laptop booted up, allowed all the drivers to be updated and was working great. Once it was turned off however it no longer booted. Tech reset it, booted it up again to it working once more, but upon turning it off no longer boots up.

Any ideas as to what might be causing the issue?