Upgrading your iPhone to iOS 4.3 using TinyUmbrella or Saurik server leaves you in infinite recovery mode loop. This is due to an extra baseband protection introduced by Apple after iOS 4.2.1 to discourage people from upgrading to newer firmwares while preserving their basebands. Semaphore, the creator of TinyUmbrella has just confirmed that tomorrow he will release a new version of TinyUmbrella which will kick out all those iDevices who are stuck in iOS 4.3 recovery mode loop.
Tomorrow: releasing a new fixrecovery that will kick you out of 4.3 recovery loop! Thanks @iH8sn0w for testing! Win&OSX ver will be avail.
If you do not want to use TinyUmbrella to upgrade your iPhone firmware to iOS 4.3 while preserving current baseband, you can always use Sn0wbreeze 2.3 for the same purpose. Just follow this guide and choose Baseband Preservation Mode in step 10. Note that upgrading to iOS 4.3 using TinyUmbrella or Sn0wbreeze (Baseband Preservation Mode) will not jailbreak your iPhone but will only preserve its current baseband.
Semaphore has already released a special version of TinyUmbrella called Fix Recovery which can kick all those iDevices out of recovery which were stuck in infinite recovery mode loop after iOS 4.2.1 restore. Just download TinyUmbrella (Fix Recovery) from official website and follow this guide on Windows and this guide for Mac if you are stuck in iOS 4.2.1 recovery mode loop.
We will update you as soon as Semaphore releases TinyUmbrella (Fix Recovery) for iOS 4.3. Stay tuned!Contact Us for News Tips, Corrections and Feedback