These issues are quite common for many Lumia users. So if your phone is stuck on 0% progress for an extended time period when trying to download a phone software update, you need to do the following to help it work.
First of all you need to make sure that your device is connected to a charger and a Wi-Fi network.
Then go to Settings > Update and security > Phone update. Tap the Download button -if you don’t see it, wait for a few minutes for the button to appear.
If you continue to have a problem with downloading the update, go to the Store > Menu > Download and updates. If there are any pending app updates, complete or cancel them.
Downloading the phone software update may take a while.
If you still can’t download the phone software update, you may need to reset the phone. To do that, select Settings> System > About > Reset your phone.
Also if your phone randomly reboots, freezes or does not switch on or if an app crashes or if you have sound problems, or if the screen is blank you can try the following fixes to solve the issues.
First charge your phone for at least 20 minutes or so and then restart your phone
Press and hold the Power and Volume down keys simultaneously for 10-15 seconds. Release and the phone will restart. After this operation, you may need to set the date and time on the phone. If the problem persists, reset and restore your phone as instructed below.
Remember resetting your phone erases all your personal data from the phone and restores the factory settings.
Before continue with the reset, make sure your phone’s battery level is above 50%. To check the remaining battery life, go to Settings > System > Battery saver. If you are not able to check it, or the level is too low, charge your phone for at least 20 minutes.
Reset your phone by using the phone settings. Select Settings > System > About > Reset your phone
However, if you cannot access the phone settings, follow the steps below:
Disconnect the charger. Press and hold the Power and Volume down keys simultaneously. 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. Release the volume down key.
Press the volume and power keys in the following order: volume up, volume down, power, and volume down.
For Lumia 950 XL users the physical key combinations differ slightly compared to other Lumias.
Now wait for your phone to reset. 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.
Go through the initial phone setup. Make sure that you have the date and time set correctly. Select Settings > Time & language > Date & time and your phone is ready to work again.