My iphone 3gs was at fw 4.1 . I made a custom 4.3.3 ipsw with snowbreeze 2.7.3 , updated it(added 6.15.00 baseband) and unlocked with ultrasn0w. After some minutes working fine,even made some calls , my iphone entered DFU mode.
I used redsn0w 0.9.6rc16 with ipsw 4.3.3 and selected "Just boot thetered right now". The iphone restarted and worked for some minutes, Then again got into DFU , but this time it is stuck.

Current status:
Iphone 3gs , BB 6.15.00(ipad) + ultrasn0w unlock 1.2.3 , windows 7 , itunes 10.2.2.14
SHSH avaliable: 4.1 and 4.3.3

What i tried so far:

1) All custom firmwares i have ( 4.1 , 4.3.1 , 4.3.2 , 4.3.3) on itunes , but get error 1600 or 1601, sometimes error 28(most from 4.1 custom). The main problem here i only have shsh for 4.1 and 4.3.3. If i dont use iREB i get error 1600 , if i use it , i get error 1601 after some minutes.

2) Redsnow and iREB. On these 2 , just after the limera1n exploit goes in(1st phase of jb) the iphone supposed to restart , but it dont , it turn off, leaving redsnow on the waiting for reboot screen. So i have to do the manual process to enter DFU so the phone can turn on again.

Most recent Itunes logs (have around 50 lol):
2011-05-17 14:06:57.256 [4668:50c]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-17 14:10:46.088 [2800:778]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-17 14:11:30.365 [2800:778]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-17 14:20:17.721 [3264:410]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-17 14:22:39.628 [4788:a98]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-17 20:08:47.155 [412:78c]: restore library built Feb 7 2011 at 06:28:58 - Pastebin.com
2011-05-19 01:17:15.416 [5868:fac]: restore library built Feb 7 2011 at 06:28:5 - Pastebin.com
2011-05-19 01:27:39.366 [5372:10f4]: restore library built Feb 7 2011 at 06:28: - Pastebin.com
2011-05-19 01:28:58.890 [6044:1068]: restore library built Feb 7 2011 at 06:28: - Pastebin.com

Main problem i suspect: the iphone cant reboot properly after the limera1n exploit , so it stays off after injecting. This way it cant install any custom ipsw to revert this status.