It looks to have failed and you've done the best test I know of (the other machine.) There is no fixing such things and if we disassemble it to try the hard drive in another case or cable the warranty is void.
Make that call.
i recently bought a s2 500gb external hard drive from samsung, worked great at first, but yesterday it started making some bizarre noises (which i later looked up in the manual, which apparently indicates insufficient power supply). It doesn't make that noise anymore, but then suddenly my vista laptop failed to detect the drive at all under my computer, and i cant find it in device manager either.
the blue light on the front of the device still flashes (and no longer beeps) so I know it is definitely connected.
I tried it on a friends laptop, shut down my laptop several times and tried using different usb ports, but no success.
I'm unsure how to resolve this now, does anyone know anything that I can do to make it work again?