my mobile not showing network showing no services
You have to optimize the range of the mobile network, see this Apple article: If you see No Service or Searching on your iPhone or iPad
https://support.apple.com/en-us/HT201415
Chcek also the Wi-Fi network, you need strong Wi-Fi network, see this Apple article: If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network
https://support.apple.com/en-us/HT204051
When Low Power Mode is On, charge the iPhone.
Wait until the battery is fully charged (100%).
The Low Power Mode will turned off automatically.
You need about 6 GB device storage.
Try also to update using the computer -see this Apple article: Update your iPhone, iPad, or iPod touch with iTunes
https://support.apple.com/en-us/HT212186