Here you can download MSM8916 based Stock Firmware for the Symphony H300 Plus Android device. The downloadable file High Compressed in an archive, You will get the Flash File after extraction. Included contains USB Driver and how-to Flash instructions.
[*] Chipset: Qualcomm MSM8916.
[*] Driver: Qualcomm Android USB Driver.
[*] Firmware Type: Infinity Chinese Miracle 2 Dongle (Script).
Firmware for Symphony H300 Plus
Build Number: L5261AE_PR2_5.1_00_12
Android Version: v5.1.1 (Lollipop)
Download Size: 967 MB
[*] Backup: During the flashing process the CM2 Dongle will erase user data from the phone. So you need to backup for restoring those files on your device.
[*] Flashing Information: The following provided firmware produced using CM2 dongle. So you need to use CM2 QLM Tool for performing the file on this phone.
[*] Device Information: This is a Cloned or UnOfficial product because we can’t find any Symphony official information on this file and Symphony manufactures Database.