I too had the problem, that the thread (tutorial ' Display Assembly ', Step 13, yellow screw) separated from the logic board. Actually I think it was broken off when I opend the phone (crshed display due to droping). You can see this here: position and removed screw and thread:
I decided to assemble the phone without this screw and thread. Up to now I did not have any abnormalities (well, I had the proximity sensor not working problem, but I think this is not related).
As an electrical engineer I consider it at least as very uncommon to use a shield or antenna as a conductor at the same time. Reasons against are: 1) bad testability of the board while not integrated into handy 2) the use of a screw is not as reliable as a soldered connection. But of course there remains a chance they do it anyhow, as space is really crucial inside such a device!
If the shield really has a jumper function at the same time: What kind of malfunction have you found in devices without this screw?
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well I tried to reattatch the jumper to only fail, I cleaned every single piece with isoprop, and tried again to only have it fail, took it to apple and they told me that they can't take off the back because they don't know how to work on iphone 4. I am just trading in for the stiff price of 199.99 for a new phone... I loose this time
crwdns2934271:0crwdnd2934271:0 Joseph Razmek crwdne2934271:0
Sorry to hear that and I do wish you better luck in the future.
crwdns2934271:0crwdnd2934271:0 oldturkey03 crwdne2934271:0
same has happened to me, many times and the same one you are referencing (1.2? or 1.4mm screw on the inside corner of the logic board, under the "U" shape on the metal frame. Try finding that thread in carpet. Anyways, I have been successful every time carefully putting it back exactly where it needs to be, then hitting it with the solder iron (dont take that literally) and remelting the existing solder, getting it to hold. Be careful, because there is a connector right there for the screen and you dont want to bridge the connections. I know may have already taken the phone back, but this is for future reference for all you googlers ;)
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