Hard Drive connected what next?

[amigakit]

Does it show up in the Early Startup Menu (hold both mouse buttons when reseting the Amiga)

Does it have any drive selection jumpers on it- these usually need to be removed.

Also did you make the drive bootable in HDToolbox?

[amigakit]

If HDToolbox did not recognise the drive, that means either the drive is defective or you need a replacement 2.5" drive cable or the cable isn't properly fixed in.

Check that the drive cable is firmly in place on the motherboard and the drive is firmly connected.  Ensure that the drive connector isn't displaced over the pins.

[amigakit]

It is probably defective then.

Another possibility is that it could be slow to startup-some old drives startup slower than the Amiga's IDE interface takes to recognise them.  This problem was fixed with Kickstart 3.1

Have you tried doing a warm reset and then testing it?  You can also cut pin 1 on the IDE cable to compensate for slow drives.