How to solve the “no SIM card” problem in Windows 10 Technical Preview
Last Friday/Saturday the Windows 10 Technical Preview for phones build 10051 was released for new devices that before this update weren't able to run WP 10 TP. However, with the upgrade an important problem appeared: the infamous “No SIM card detected” problem.
According to a Support Engineer from Microsoft: “This is a known issue that occurs for a small portion of users who upgrade to the current Windows 10 Technical Preview build (10.0.12534.56)”.
Small number of users or not, if you are having this problem here are some instructions to get the problem solved but as Microsoft said, it's advisable to have a backup of your photos and most valuable memories before you proceed.
It's important to know that after following the instructions shown below, if the reset works, you will have Windows 10 Technical Preview running! (and not back to 8.1!). There's a confusion around about using the recovery tool and resetting from the menu.
Checking that there's a backup
If you have been using your phone for a while and you haven't changed the default settings, then there's a big chance that a backup of part of the data has been already done automatically.
You can verify this by going to Settings > System > Backup. If you want to be sure you can check one drive online or also the Windows Recovery Tool
There are also some apps to save contacts and messages that should be checked if a backup is required.
Going back to a clean and working Windows 10 Technical Preview for Phones
1. Go to Settings > System > About > Reset my device
2. Accept the first warning
3. accept the second warning
4. The phone will restart and the spinning wheels will appear. They might be running for some minutes without any apparent progress but be patient and shortly the white bar will start to fill the centre of the screen
5. After the spinning wheels finish their job the phone will restart automatically then you will see “Nokia” and a black screen
5.1 At this point some old models were with the black screen light on for a while until power was pressed and quickly a “Not for resale” message in red with a Windows Logo will appear.
6. Later, after tapping power softly if the phone stopped responding, or after waiting patiently, a “Welcome” screen with white background to choose the language should appear.
7. Complete the information requested and when you get to your Microsoft account enter the same account that you used to have in your phone.
8. Microsoft will ask you to be tracked and some other question but then the glorious “Restore phone” option will appear. Select the phone that you want to restore and click “next”
9. A screen confirming the restoring should appear and around 17% it might stop and a screen showing “Verify your identity” will appear.
10. If the screen appear, use the alternative email and another device to get the validation code and tap “next” and it should continue (this time a bit more slowly).
11. The restore will finish and either you will get a message letting you know that not everything was restored or you might get one that says that everything is fine click “OK”
11.1 If you have had accounts to check the email you might see a screen “Restored accounts” and you will need to enter the password again and click “next”
11.2 In some occasions (Lumia 520 and Lumia 625) Windows 10 TP just died here (at “Restored accounts”) and tapping next didn't have any effect!. After tapping and waiting enough it was necessary to press and hold power to switch off the phone, wait until it was off and switch it on again. By doing this the phone entered into an infinite loop until it finally went back to its traditional black and shown “Welcome back”
12. The screen “Almost done…” will appear asking to use the data connection. I chose “No” and then it went to the screen “Thank you for using Nokia”
13. “Resuming…” and back to life!