Why my iPhone shows no service?

Hello.

I had Iphone 3gs 16GB and the ios was 6.1.6. It was from England and the carrier was O2. So for that I did the jailbreak and it was correct but after jailbreak it shows NO SERVICE. I asked lot of poeple and read some commentaries about that and I decided to Jailbreak again but also click "Install IPad Baseband" in redsnow. Then Jailbreak was going but It shows me "ERROR put your iphone..." in something but i dont remmerber "and then try redsnow again".

So after that It doesnt worked. I pluged in charge put show Chargong with red colour and shows Apple for some minutes and then sweaches off. I tried again but doesnt works.

The I went to Proggrammer and he told me that he must install Ios 4 , then jailbreak, then upgrade iphone to 6.1.6. He installed ios 4 and jaibreaked but in boot. So now my iphone is in boot jalbreak. I didnt sweached off my iphone because the proggrammer told me that if i do this my iphone will be die.

I wached that he cant do that and I decide to fix this by myself but only with your recommendation and good ways to fix my iphone.

Please help me in this.

Thank you for your attention!