All,
The problem with the wifi greyed out is that the IOS update has made the wifi chip overheat so the phone disconects it. Apple are not admiting the fault and will lose good customers over this. I have the same issue and have been doing research into it as this is my first Apple product. I also am an Engineer in the Printing Industry but deal with suppliers, Customers and Warranty/Quality claims in my day Job.
As everyone has discovered there is a short Term fix by using the hair dryer/ fridge method but for how long?
Some repairers not Apple will reflow the chip but it is expensive because the phone has to be taken apart. They will also only give you a limited Guarantee. Talking with one Phone fixing Company in the UK they will not touch the issue because the solder used these days is lead free. This is harder to solder than leaded and more liable to break under vibration. Hence if fixed it may happen again! In the aircraft Industry they still use leaded solder as it flexes and is more resistant to vibration.
Apple will not let us down grade the IOS and this may be for two reasons. If you update Firmware then sometimes it cant be reversed. It may also be that if the chip has overheated and damaged the solder then reverting back to the old IOS will not fix the problem.
Apple should admit the problem and come up with a fix for people like us who have a device out of Warranty. I dont mind paying a small price to fix the unit even though not happy about it.
I am disapointed with the Apple service as they sent me a message to update my unit but have washed there hands of the issue. My suppliers would not do this to their Customers and we would not do it to ours in the Printing Industry If we did a firmware change which broke a Machine even if out of Warranty we would fix it to kae sure the Customer bought another Machine from us.
I dont thinkm I will buy another Apple device unless they respond and do something about the issue. What we need is the press or some importanat body to take up the cause.