The first sign of trouble on my phone was gps not working , then I noticed poor WiFi and Bluetooth range. I followed the steps for this repair - I think two of the connectors on the antenna flex had just popped off, but I replaced it anyway as I had bought the part (under £2 from replacebase.co.uk). Now gps, WiFi and Bluetooth all looking good again. Great guide, thanks. Not too difficult, just need to be organised with the screws.

OK, I spoke too soon, all works fine EXCEPT the battery percentage jumping around (e.g. suddenly going down from 54% to 1% - then on rebooting the phone it came back up as 33%). I have seen this problem before with a bad battery guage, and also with a bad charging IC, but I'm not sure whether a bad lightning port assembly could also cause this? I will have to start replacing things again to track down the problem...

I had the poor signal issue after using a part bought from Amazon. After a lot of fiddling around, I decided to replace original part and signal was fine again. I then bought a part online from 'replacebase' in the UK, fitted that and all works fine. So my experience was that it was a faulty part rather than anything subtle about how it was fitted.