If you mean you actually fried the chips on the control boards installed on the HDD's, stop and take a deep breath. There is a big probability that the data is still readable - as long as you don't play games.
First of all, if you don't feel VERY comfortable about changing the control board of a HDD, please DO NOT attempt so. Find a professional guy to find a suitable card and replace it. Depending on the brand and model, you may be unable to find a replacement. In this case, send the HDD's to a data rescue company. This will hurt financially, so be prepared.
If you mean something else by frying, then I'm not sure what you mean, please be specific.
Good luck,
Engin