So, I don't know much about this stuff whatsoever, but long story short... I saw my supervisor playing NES games on his iPhone, asked him how to get them on mine, and within a few minutes, I had an emulator and a couple roms to work with. Cool.

He mentioned that if I upgraded to 4.0, I would lose the jailbreak and related apps. I didn't play them much since its tough to play NES games on such a tiny screen anyways and the novelty wore off quick... so I tried to upgrade. Wouldn't work. I figured if I "erased all content and settings", maybe that would help. Apparently that was a big mistake. Now my phone is in FDU mode and I am just getting the error ". I'm trying to restore and upgrade to 4.0, and all I'm getting is the error "Device isn't eligible for the requested build". I have no idea what to do. I"m stuck on a black screen. If I hold the power button for a while, I'll get the apple logo. But thats as far as it goes. Any help would be greatly appreciated.

i did a quick google search.

what kind of phone do you have 3G, 3GS, or 4G iphone?

i think there is a specific firmware you have to restore to or that you can't restore based on the model and whatever JB you did.

I have a 3GS. The only info that I can really tell you about the jailbreak was that it had the application Cydia. Other than that, the only thing I can say for sure was that I could play NES games, haha.

I've tried uninstalling and reinstalling iTunes, doing the hold both buttons and then releasing the power button while continuing to hold the Home button so that iTunes recognizes it, and keep getting the same message.

i don't jb so i have no idea really.

maybe try to go to a lower firmware first before going to 4.x
like 3.1.3 you can get them here: http://www.felixbruns.de/iPod/firmware/

maybe have your supervisor look at it before you turn it into a permanent brick.

True. I'm going to bring it to him tomorrow if I can't figure this out. I'm super pissed, as it's my only phone, just bought it recently, and I'm closing on a condo this month... so that means no money, and no way for my lawyer, loan officer, realtor to contact me. Ugh.

Thanks for the suggestions. I'll try what you said about the firmware tonight.

Apparently only the most recent version of IOS firmware can be used when restoring a 3GS. But I used the site you pointed out to download and restore it with 4.2, since iTunes wasn't assisting me to do so. Thanks again for the assistance, it ended up being a big help.

But now, the new firmware requires the new iTunes. And the new iTunes needs the most recent OS X. Looks like I'm spending money with Apple either way. Ugh.