Intermittent signal or "No service" after water damage
I recently fell in the water, carrying my iPhone in my pocket, but managed to crawl up after like 2 seconds. After getting out of the water the iPhone was obviously wet but not much more than from used in heavy rain I would think.
My first reaction was to try to shut it off and let it dry, but the phone kept rebooting, which I later learned was due to water in the dock connector that made the iPhone think it was connected to a dock/charger. Since I had no tools at the moment I simply tried sucking water out from the dock/headphone jack and let the phone rest for a couple of hours after which I was able to turn it of and did not use it (and the very sparingly for a couple of minutes) until a couple hours later.
Once I was back home I figured the phone had probably dried out, and I was left with a weird problem that disabled all sound output except for Siri and ring tones. I learned this was due to corrosion in the dock connector and ordered a new one which I also managed to get replaced using this wonderful guide.
Now, the problem
About two weeks after the incident, on the same day that I finally had time to exchange the corroded dock connector my iPhone suddenly lost its cellular signal, when reboot after a full battery discharge (the first one after the incident I think). This lasted for a couple of hours as I tried the usual tricks of airplane mode, rebooting and resetting the network settings. At best I was able to get a couple of minutes of 3G.
I figured the dock connector might have given up completely and proceeded with the replacement which went fine, and the sound/volume buttons etc. has worked flawlessly since. I tried a few phone calls after the installation to make sure the new mic and reattached antenna was OK and everything seemed to be working fine.
24 hours later I was back with the "No service" message. Sometimes the phone connects spontaneously for a couple of minutes, after which it will either go back into "No service" or display full bars 3G without actually being connected. In this state outgoing calls will dial silently for a couple of seconds before failing.
I reopened the phone today today to check all the connectors, the antenna connectors running from speaker and clean away any fingerprints (which I read could affect the signal). This procedure game me approximately 2 hours of good signal, but now I'm back with "No service" again.
So, I've been trying to read up on what to do next. I've come to think there must be some corrosion elsewhere in the phone.
As my phone works fine for brief periods of time I would not suspect I have lost the blue inductor coil that seems to be responsible for signal loss in some occasions. I would also guess that all connectors are in place. Otherwise I would get "No service" all of the time, right?
I understand the antenna (connector only I guess?) is located close to the dock connector, but it seems to be such a simple piece of hardware it would hardly be affected, and in which case I would definitely be able to see corrosion/rust. I have in fact seen traces of corrosion on the screws near the SIM tray, and some green corrosion thingy on a component underneath that I clean away with alcohol.
I starting to think my best option is a complete cleaning with alcohol, but I also fear that might be a little late now? In that case, does anyone have an idea on a specific component that I can clean/replace to address this issue?
I'd be extremely grateful for any tips or ideas regarding this issue.
EDIT: Just thought I'd add, my phone looks clean inside. Not anything like that pictures in this cleaning guide.
You can take the rusted screws and soak them in white vinegar and it will remove the rust thus helping the antenna ground. Clean everything that is green or white powdery residue with alcohol, especially the antenna cable and connector and scrub corrosion gently with a toothbrush and you should be good to go.