LaCie external harddrive not mounting

Hello

This is my first time here.

I have a problem that goes back a few months. A Lacie 1 TB harddrive suddenly stopped working. I may (not sure actually) have used the wrong power lead. Anyway it stopped working and after a lot of searching for information I came on the idea of buying a replacement drive (it is actually a Hitachi drive in the Lacie case) and swapping the exterior circuit boards.

After a few months one actually came up on ebay and I got it, replaced the circuit board and the drive now fires up. I can see it on disc utility, but it won't mount. I've even tried it on a PC, but it can't see it even though it knows its there.

Disc Utility won't let me do anything with it and I tried downloading the trial copy of Disc warrior, but that failed to be able to fix anything as well. I'm more than happy to pay for software that will help fix it, but need to work out what I need to do. Is it salvageable, or is it completely gone?

I can fix things usually, but this is my first time with such a problem with a external harddive.

Can anyone help?

Many thanks

Was the circuit board a direct replacement and will the firmware work on the new one?
Not sure you checked but the power supply is what I see go bad in the Lacie's in field although it still outputs power its lower than spec calls for.

Thanks for the reply

The circuit board is a direct replacement, but I'm not sure about the firemware. I don't know how to check that.

I always go to mfg.'s website and get it. LaCie is the premier manufacturer of high quality digital storage.