Issue: Your Nokia Lumia with Windows Phone 8.1 or Windows 10 Mobile can’t get past a solid pale blue screen at startup. You’ve got the blue startup screen of death!

Solutions: Forced Restart, battery & SIM removal and re-seat, or a full reset (all data will be lost)

Forced restart with buttons
- Hold Power and Volume down keys at the same time for 10-15 seconds
- Release buttons and the phone will restart
Remove battery and SIM card
- Microsoft Support Video – How to insert SIM card (Shows battery @ 1:00m)
Full Reset #1 – via power and volume keys
Microsoft has excellent steps and instructional images here: Reset my phone
* you will loose any local data or settings that have not been backed up
1. Make sure you’re 50% charged or more
2. Disconnect Charger
3. Press and hold the Power and Volume down keys simultaneously.
4. Release the keys when the phone vibrates and then immediately press and hold the volume down key until the phone displays an exclamation mark (!) on the screen.
5. Release the volume down key.
6. Press the volume and power keys in the following order: volume up, volume down, power, and volume down.
7. Wait for your phone to reset.
8. During the reset you will see gears rotating on the screen for up to 5 minutes, after which the screen goes blank for ~30 seconds and then your phone will restart.
9. Go through the initial phone setup.
10. Make sure that you have the date and time set correctly. Select Settings > Time & language > Date & time (Lumia with Windows Phone 8: Settings > date+time).
Full Reset #2 – Windows Device Recovery Tool
* you will loose any local data or settings that have not been backed up
1. Download and install the Windows Phone Recovery Tool to your PC.
2. Launch the recovery tool and connect your phone using a USB cable. It probably won’t detect the phone so click My phone was not detected.
3. In the next screen, click your phone, wait a few seconds, and you’ll see your phone information and the software available for download to roll back to a previous operating system. It’ll say something about the phone being in UEFI mode. To continue, click Reinstall software.
4. Next, the recovery tool will warn you to backup all your data, settings, and apps before continuing, as the rolling back process will delete all the previous data in your phone. Click Continue to proceed.
5. Now, the recovery tool will download the image from Microsoft’s servers and restore your phone to Windows Phone 8.1. It’ll take a while, but just leave it alone and let it work its magic.

Windows Phone - blue screen of death — Windows Phone – blue screen of death

Windows Phone - Reset Exclamation — Windows Phone – Reset Exclamation

Windows Phone - Reset — Windows Phone – Reset

Windows Phone - Reset Gears — Windows Phone – Reset Gears