iPhone 4.2.1 (Jailbreaking)

===Restore FAQs on iOS 4.2.1===-Download Slide to unlock killer
-Slight battery draining issues on 4.2.1
-Runs on "M1 Singapore 9.0" network
-Current iOS which is stable for restore on iPhone 4, due to 4.3.1 has antenna and lagging issues.

===Initial Step===Save SHSH!

===Files Required==="zlib1.dll"
"Tinyumbrella.exe"
Fixrecovery (from tinyumbrella site)

===Installing Section===1. Restore the iPhone using TinyUmbrella + "iTunes" mode.
2. Click the "Check" and continue. Now, shift + click the restore button.
3. Wait for installation to complete.
4. Use Fixrecovery421.exe (be sure that iTunes program in running) to fix the looping issues.

===Device Firmware Update (Recommended for restoring)===
Step One:-
Press and hold the "Home" button and the "Sleep/Wake" button at the same time.

Step Two:-
After exactly 10 seconds release the Sleep/Wake button.

Step Three:-
Continue holding the "Home" button for about "8 seconds" until you iTunes pops up a message telling you that it has detected an iPhone in recovery mode.