OK! my bet is the original PSU popped and took out the hard drive in such a way that it is now dead shorting to ground.
So then you connected the new PSU upto the dead hard drive and because of the dead short blew that one up as well.
This is an extremely common problem with cheap no name PSU's and the reason why PC professionals will always use branded quality power supply units.
Quality PSU's also have more advanced failsafe circuitry that in the event of failure very rarely damages other hardware.
Enermax, Fortron, Vantec, Zalmam, Antec etc
Martin
Replying helps further our knowledge, without comment leaves us wondering.