I had given my iPhone4 for a service for changing its broken display. After that I used it for a day and then the problem started. It was showing the apple logo and was going off whenever i tried to switch it on. Tried power button+home button restart, same response.
Here is how i solved my issue in a DIY way.
I didn't have an iPhone screw driver. So I used a pointed knife to open the two screws at the bottom of the phone, near to the speaker and microphone holes. Slided the back cover of the phone(back cover i mean is, the part of the phone which has a printed apple logo on it). After sliding up, it should come out in your hand. No force needed.
Now the back portion of your phone is open exposing the battery, some antennas and contacts. You will be easily able to locate the battery connector(small rectangular, stainless steel with again a screw) Use a proper star screw driver to open the connector or if you are my type, use the 'magic knife'. I was not worried about the scratches which are going to come on the screw because, This screw is inside, my phone is pretty old, screw is cheap, service centers were far, didn't have time and repairing was so urgent.
While opening this connector screw, you should be a little careful because when you remove the connector screw, there is a small piece of metal which will come out, this is the contact for antenna. Which means, the battery connector and the antenna, these two things are fixed with a single screw. So when the screw is removed, you will be able to take out the clip-on 'battery connector' along with this small piece of metal. Open up the connector, see whats inside, use a dry brush to remove any dust or debris stuck inside the connector.
In my case, I was lucky enough to locate a dried piece of glue which was disturbing the connection.
Clear it off. Put back the connector by aligning it in place and giving it a push. Now at this point, if you are to eager to see whether the phone is working, go ahead, switch it on. Any luck? If not, remove the clip on connector and visually align it and put it back again after a little more cleaning. This time, press and hold the connector with your finger to give it a proper pressure to help the contacts touch if any loose contact issue is there, and switch it on. It should work. Put back the screw. Avoid tightening more if don't have the proper tool. In my case, my Passion of working with automobiles and heavy stuffs, I had a habit of over-tightening and breaking these delicate electronic components. So don't do that, Knifers, leave the tightening part for later. Some day you might come across a proper tool, that time you may open your phone again and tighten the rest. For time being, just make sure it is not too loose to stick out to touch the cover.
Time to put back your phone in one piece. Place the back cover cover a little up, slide down to lock, put back the two screws at the bottom. Hope you should be good to go.
Contact me via call,sms or whatsapp, if you got any doubts or to discuss any interesting DIY fixes like this. I dont have any blog or website. This is my first attempt to write a matter in such a blog. Happy living Dears..
Roshan K Kumar