Help me please

I attempted to flash my xbox 360 a couple months ago (benq drive). I was way over my head and thought I successfully flashed my console, but when I turned it on. Guess what? 3 red rings.

I doubt it has something to do with faulty hardware, but the I must of screwed up the software by doing a bad flash job.

I need some help, I need to undo whatever happened. I connected the console HD to my motherboard and the xbox is on, but my computer isn't reading the harddrive, (I think because none of the programs like dosflash isn't seeing anything).

I have the original firmware (I backed it up incase something like this happened)

What should I do?