|Some motherboards with SATA I controllers have problems configuring SATA II hard drives. Most, but not all, SATA II hard drives have a throttling jumper on the back of the drive that forces the drive to run at SATA I speeds. That may be your issue. Set the jumper for SATA I.|
SATA hard drives are hot swappable so connecting the data cable under power shouldn't have a negative affect. Connecting the power cable could, but then the drive would not be identified by the BIOS. This could be you problem. If so, there isn't much hope. Have you tried using a hard drive fitness test from the manufacturer? You boot to a disk with the fitness test on it to run. If that can't see the drive then something is fried on the drive. Possibly the PCB (printed Circuit Board). It is possible to get a matching PCB off a working drive and change it. The PCB must match exactly. Model of drive alone is not enough. Firmware and other factors matter. Professional recovery may be in order.
Have you considered the issue may be the SATA controller or data cable? Verify the controller is enabled in the BIOS and the controller is functional. Try a working cable.