I initially screwed up my 1.1.2 OOTB phone by running baseband downgrader. Then I lost my wifi etc. Finally, I was able to solve my problem. I browsed through lot of forums and got help from them. I want to contribute back to the community. Over the last week, I was writing a detailed blog on the steps that I follwed. There are photographs explaining the disassembing and scratching the testpoint. I also tried to list the solutions for common problems. I hope this will be of help for the other people who are facing problems.
When I came to post this, I came to know that there is a software unlock, for 1.1.2 OOTB and 1.1.3 OOTB phones. So, it is advisable to use software unlock for the people who did not start hardware hacking. But I know that there are lot of people in a limbo state with bricked phones. This post might be of help to them.
The entire tutorial might be boring to read. So, I broke them into steps so that people with a specific problem can read only the step that is of interest to them.
Here are the steps and the corresponding links to my blog.
Summary: Bird's eye view of the whole process.
Downgrading 1.1.2 firmware: How to downgrade to 1.1.1 or 1.0.2. jailbreaking 1.0.2 using ibrickr + activation.
Gathering resources: Links to various sources to get the required tools
Disassemble Iphone: Tips to open the iphone case & the metal cover with photographs.
Scratching A17 Line: Tips with photograhs
Bootloader downgrad: How to use ienew + iunew. Common problems & solutions.
Restoring baseband & unlocking: Restoring firmeware, unlocking and patching to use the phone outside US(iworld, phone # fix)
All the best.
Please free to point any discrepancies. I will fix them in my blog.