Software Download Link-
Walton_Primo_E4+(Android 5.0 )
1. Extract Downloaded Firmware.
2. Install driver software
3. Open SP Flash Tool
4. Open Download Agent and select MTK_AllinOne_DA
5. Open scatter_loading and select scatter file
(Walton_Primo_E4+(Android 5.0 )\Primo_E4+_Lollipop\MT6582_Android_scatter)
6. Click Firmware Upgrade
7. Now select Download and then connect USB cable with mobile (mobile must be off). If you see below image, it means that mobile is detected through Usb cable.
8. Then start downloading/flashing firmware
9. When it shows Download Ok, it means the installation/flashing firmware is completed. Enjoy Lollipop.