Unlocking G1 After Repair

[Prymate]

I bought an unlocked G1 on eBay awhile ago, used it on AT&T, and later had to send it in to be repaired. They replaced the main board, so when I got it back it was locked once again.
I've bought unlock codes from 2 different sites since then, and both refunded my money with an email saying they were unable to unlock it. Also, I'm not a T-Mobile customer, so they won't give me an unlock code.

Is there any alternative way I can unlock it now?

Thanks!

[Michel Dover]

I bought an unlocked G1 on eBay awhile ago, used it on AT&T, and later had to send it in to be repaired. They replaced the main board, so when I got it back it was locked once again.
I've bought unlock codes from 2 different sites since then, and both refunded my money with an email saying they were unable to unlock it. Also, I'm not a T-Mobile customer, so they won't give me an unlock code.

Is there any alternative way I can unlock it now?

Thanks!

It looks like a faulty unit, assuming that you have valid unlock codes. There are some of them in the market: stolen phones, beta units and more.

[Prymate]

Well as I said, the main board was replaced, so in its current state it couldn't be a stolen phone or beta unit. It's not an original unit at all at this point, so do you know which component could be causing this, if one is faulty?