Downgrade from iPhone OS 4.0 beta to v3.1.3

After the announcements about Apple iPhone OS 4.0, I immediately went to the Apple Developer site and downloaded the beta version. I never installed a beta version of the iPhone OS before so I thought that it would be stable enough for daily use. But it turns out that if you have only one iPhone (like most of us) then I would not advice you to install it yet.

This is what I encountered during the last couple of days:

• Because I own 3G, I missed the key feature of Multi-Tasking. And with no multi-tasking what’s left?
• Folders: they work but for me they don’t add something I was missing. It’s also a bit difficult to darag and drop apps in and out folders.
• Mail: Nice new feature. Now I can read both my mailboxes from one list. This one actually is very nice.
• I could not test iBooks, iAd, Game Center.
• Some applications didn’t work correct anymore. One of the apps I use a lot and cannot miss is TomTom, but it became very unstable. I also encountered minor issues with other apps, but most of them worked.
• The reason why I really wanted to downgrade was that I had to reboot/reset my iPhone more in the last couple of days, then since I owned it.

And (being new to installing beta firmware) I found out that you could not easily revert back to the current 3.1.3 version of the OS. After a bit of “Googling” and experimenting, finally these blog posts helped me out :

• Just Another iPhone Blog: Quick Tip: Downgrading 4.0 beta to 3.1.3
• iClarified: How to Put an iPhone Into DFU Mode

This worked for me, so I hope it works for you too. I now have a stable phone again