I'm trying to sell my phone (3g, on 3.0) but cant sell it since the beta will expire and the buyer will be left in the dark as to how they should fix it. I would also prefer to sell it unlocked, but dont know if i can unlock it after going to 3.0, i've heard its tough, if not impossible.

Basically i need to know everything i need to know on downgrading to 2.1 (or 2.1.1 or what ever it is) and hopefully unlocking so the buyer has the option of T-Mobile.

I'm on OS X 10.5.5 and any help you can give me would be greatly appreciated, thank you.