These jigs are used to force the phone into download mode where you can use odin to restore the phone.. Hard bricked means that the phone does absolutely nothing when powered on. No lights or anything at all. The jigs can restore your hard bricked Galaxy S2-S5. I purchased them while to diagnose my own phone issues. My motherboard ended up going bad. Remember, you can always purchase a new motherboard for your Galaxy phone from ebay or other sources for about $50-$75. Just make sure it has a clean ESN if you do..
I offer these because one can't be afraid of failure..
Check out amazon.com and ebay.com for various jigs for galaxy cell phones. it's a good place to start a search for a jig for your model phone..