Instructions
GO TO DFU MODE (power+home for 10 seconds then home for 10 seconds) Phone will remain completely BLACK. If not repeat previous step.

Then select 1.0.2 firmware for restoring.

At the end you will have an error.

THAT's NORMAL!

Now get IPHUC and issue:

cmd setenv auto-boot true

cmd saveenv

cmd fsboot

You just downgraded!