To update Android software in Xolo A500 officially :
- Go to Settings → About device → Check for Updates → Select Update now
- Ensure that you are connected to mobile internet or wifi internet.
- Keep battery charged about 60 Percent as it will take considerable time to finish the process.
To update manually in XOLO A500 , from Kitkat to Lollipop or Marshmallow Upgrade:
- Root your device
- Install a custom ROM
- Download the suitable package from android forums like xda developers.
- Follow their procedure to upgrade new version of Android in XOLO A500
- Complete the Process
Backup is recommended before manual upgrade. And usually , rooting the device will void the warranty of the device.