It sounds like the cable may have been in the wrong way round. The old 2.5 inch drives have 44 rather than 40 pins, the extra 4 carry the power.
It's a really bad design flaw. The larger 40 pin connectors used on 3.5 inch drives can't usually be inserted the wrong way round and yet the worst that can happen if you do is that it doesn't work until you fix it. Making the same mistake on a 2.5 inch drive means you are potentially pumping 12V straight into a signal pin.
As suggested above, try the machine without the drive attached. Hopefully it still works at least.