Nokia 1520 Microphone problems

My original 1520 developed this fault shortly after having its screen replaced under warranty. Sent it back for repair and they replaced the handset with a new/refurbished one.

I received the phone today and straight away restored my phone using a backup linked to my account. Someone called and the mic doesn't work again!

Unfortunately I didn't check if the mic worked before restoring.

Tried all the usual things like resetting, wiping phone, phone recovery tool with no luck.

Emailed Anovo (the authorised repairer) to see if they can advise what to do. If not i will have to send the phone back for a 3rd time in a row.

I also thinks its a software problem.

Yes my 1520 is on denim. Bluetooth and wired headsets work just fine. Any direct microphone use with the handset, such as calls, video, note taking and Cortana type verbal input - the microphone does not work.

and as per my earlier post, I again changed out the microphone board (for the second time) and had the same results. Direct handset microphone worked for about a day. Then completely stopped. And when it was working, it was work perfectly. I even had the "Hey Cortana" feature working.

now I need to check my update history to denim, because when I first got the phone prior to denim, I had the microphone issue only with calls. All other functions worked fine. Then at some point after the denim update, the microphone problem was prevalent across the board.

I've run across a discussion at Windows Central that suggests that the problem is Denim. Can anyone confirm that they are on Denim and have no telephone mic pickup? Or that they are not on Denim any longer and no longer have the problem?

I'm on Denim with 8.1 update 1 and have this problem. I will keep my eye on it when I move to 10.

How do you know this? I'd like to know where you're coming from before I take it to a repair shop and get them to change the mic. I have to pay myself because no more warranty. Thanks

extremely helpful........