Today, I managed to install iPhone OS 3.0 on my iPhone 3G after a little trouble.
The download process went smooth, but the trouble started after iTunes began to prepare the iPhone for the software update. It failed… twice. Error 1604. I was directed to the following page each time:
http://support.apple.com/kb/TS1275
I restarted my computer to no avail. My iPhone was staring at me with a black face, and the backlight was going strong. I was slightly worried, but I remembered going through my iTunes folders a few days before. I navigated to the directory containing my iPhone 2.2.1 restore file and double-clicked on it. It started the restore process. A half-hour later, my iPhone was restored to factory settings and was re-activated. iTunes prompted me to download new carrier settings from my iPhone carrier (Rogers) and asked me if I wanted to restore from backup. Next, I was prompted to restore from a recent iPhone backup and was good to go. However, the software restore didn’t go as planned…
I noticed a new Voice Memos icon on the iPhone. Right then, I knew it was running 3.0 instead of 2.2.1. I was a little puzzled. Even though I double-clicked on the 2.2.1 restore file, iTunes decided to use the 3.0 software (in the same folder) for the restore. Hey, I’m not complaining. It worked perfectly, and all my contacts and applications are available for use.