iPhone 3g 4.2.1 and 6.15.00 bb

[marytran]

I have an iPhone 3g 4.0.1 with iPad baseband 6.15.00 jailbroken and unlocked.
It was working fine until it started turning off on its own for a couple days.
It got to the point where it got stuck on apple logo. I tried restoring it many times but there would always be an error. I guess it was bricked.
I paid someone to fix my phone. It took him about two days to "fix" it. He updated it to firmware 4.2.1 with the same baseband.
I just got it back today and it still won't turn on, still stuck on apple logo.
Help please?

 

[Applejuiced]

Why did you pay him if it didnt turn on?
Maybe it has a hardware problem?
Also you will not be able to restore it to any official firmware ever again.
What you need to do is find or create a custom 4.2.1 IPSW created with pwnage tool.
And then put the phone in "pwned DFU mode" and then restore to that custom JB firmware thru itunes.

 

[WalkTheDino]

Sounds like exactly what I did.
see https://forums.macrumors.com/showthread.php?p=12165124#post12165124 for potential solutions, but none have worked for me so far. If something works for you, please post!