Jailbreak an already unlocked 3.1.3 iPhone 3G?? Will it relock?

I got my hands on an iPhone 3G (3.1.3) and it's unlocked to T-Mobile. It looks like it was jailbroken but Cydia won't load. I want to re-jailbreak it (or fix the jailbreak), and I've been trying to find a straight answer all morning!

Since it's already jailbroken (or attemped, or got un-jailbroken....idk) and Cydia won't work now, what tool can re-jailbreak it or fix Cydia and NOT affect the unlock to Tmobile?

The Version is 3.1.3 and the baseband or "Modem Version" is 5.12.01.

Would I have to re-jailbreak it and re-unlock it? Or just redo the jailbreak and all is well with the unlock? Thanks guys, sorry for asking so many questions, just want to get this straight again!

If you goto www.redmondpie.com all jailbreak instructions for each iOS are described on there. You could always update to the latest iOS then jailbreak again. This would put Cydia back on for you and leave you with a virgin iPhone to customise as you wish.

With regards to unlocking I'm not entirely sure.

Edit: ultrasnow 0.93 can jb and unlock all iOS and basbands apparently. Isn't google a wonderful thing.

Thanks for the reply. I thought about updating to 4.3.1 and re-jailbreaking. But wasn't sure about the unlock thing. I just searched and searched and couldn't find a recent post with the information I was seeking. I see all this about re-locking when I connect to iTunes and updating and then I see that some jailbreaking tools are not to be used with unlocked phones and stuff. So I just couldn't find a good answer....so I thought some iPhone pro around here could help me out! Anyone else with any other suggestions about jailbreaking and unlocking?

Does cydia just crash? If so you may have bad picture files saved. Mostly from emails or the web. Affects cydia for some reason. Try saving them and removing them. Hard reset and you should be good again.

yh send it me i will sort it for you :)

I lied....lol. I said "I got my hands on", when I really don't have it quite yet. A friend of mine is getting a 4G and is giving it to me in exchange for some computer work. So soon I will have it "in my hands" and know for sure if it crashes, doesn't load, or what. Probably something simple and dumb, but all this info on the net is overwhelming, and couldn't get a straight solid answer about jailbreaking while unlocked. Just seen alot of "baseband" this and "relock" that....so I thought I'd ask before hand to get a jump start! I'll get it sorted when I get it! Thanks guys!

Well if you want to update to latest version of iOS then you have to use a custom .ipsw file.

If you just want cydia to stop crashing then simply re-jailbreak it. Basebands can only be updated via .ipsw updates. (A.K.A Connecting to itunes and updating)