Preparing Phone for warranty - Removing custom rom /eng-off r-off etc

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http://forum.xda-developers.com – I Double checked with HTC ITALY and If I send my phone rooted etc then I will not pass through warranty.. soo I need to restore my DHD back to "stock" with root / radio / eng and all stuff back to original settings (and normal rom again). From what I gathered my steps would be: 1. flash using the HTC program the original rom from their website 2. use visionary to reroot my phone? 3. One click Radio S-OFF tool to reverse that setting But I'm kind of getting lost on the actual "steps" or sequence, and I'm worried I might brick my phone, could some one give me an (HowTos)