How Can I Update My Local Brand Walton Primo GH6+ from android 6.0 to android 6.0.1? - Android Q&A, Help & Troubleshooting

Hi there,
I am From Bangladesh and I am Using Our Local Brand Walton Primo GH6+. It is android 6.0 Os based which troubled me battery drain problem. I want to upgrade it from android 6.0 to Android 6.0.1 bug fixed rom. and I also don't know which brand they re-branded as their Brand. if it is not possible to upgrade my android smartphone 6.0 to 6.0.0 then there any procedure i can downgrade it from android 6.0 to Android lillipop 5.1.1? I create an account named Soummoni but I didn't understand how my post became guest post? extremely sorry for that.
for More details I have provided a details which can describe My smartphone.
FEATURES:
OS: Android OS, v6.0 (Marshmallow)
Chipset: No official data
CPU: Quad-core 1.3GHz
GPU: Mail 400
Sensors: Gravity, Proximity, Light (Brightness)
Messaging: SMS (threaded view), MMS, E Mail
Browser: HTML
Radio: FM Radio with recording
GPS: Yes, with A-GPS
Java: No
Color: Golden, Space Grey
Miscellaneous: – Screen flash with low light selfie
– Multiple user access
– Professional camera mode
– USB OTG support
– Capture image while recording video
– Power Management
– One clean
GENERAL:
2G Network: GSM/GPRS/EDGE 850/900/1800/1900 MHz
3G Network: UMTS 2100 MHz
4G Network: Not supported
SIM: Dual SIM (Dual Stand-by), (1 is Micro SIM, 1 is Mini SIM)
Announced: June 2016
Status: Available
BODY:
Dimensions: 145 x 73.14 x 9.7 mm
Weight: 176 gm (with battery)
DISPLAY:
Type: IPS capacitive touchscreen, 16.7M colors
Size: 5.0 inches HD, 1280 x 720 pixels
Multitouch: Yes,
Protection: Corning Gorilla Glass
SOUND:
Alert Types: Vibration, MP3 ringtones
Loudspeaker: Yes
3.5mm jack: Yes
MEMORY:
Card Slot: MicroSD, up to 64 GB
Internal: 16 GB ROM, 2GB RAM
DATA:
EDGE: Yes
GPRS: Yes
Speed: 3G/HSPA+
WLAN: Wi-Fi b/ g / n, Hotspot
Bluetooth: Yes, v4.0
USB: Yes micro UsB v2.0
NFC: No
OTG: Yes
OTA: Yes
CAMERA:
Primary: BSI 8MP Autofocus with LED flash
Features: Back illuminated Sensor (BSI), Touch Shot, Face Detection, Digital Zoom, Self-timer, Auto-Focus, Touch Focus, Smile Shot
Shooting Modes: Normal Mode, Professional Camera mode, Face beaut, HDR, Panorama
Video: Yes, Full HD, 1920 x 1080 pixels
Secondary: Yes, BSI 5MP with screen flash (Brighteen the skin in full Brightness with White Backlight)
Features: Sensor-Back Side Illumination (BSI), Touch shot, face Detection, Self-Timer, Wide Angle Selfie, Mirror Effect.
Shooting Modes: Normal Mode, Face Beauty, Wide Angle Selfie
Video: 720p HD
BATTERY:
Battery: Li-Ion 2000 mAh
Stand By: –N/A
Talk Time: –N/A
they have provided a flash tool but after using that the battery drain problem increased .please guide me what to do.
Thanks
Soummo

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Use a custom rom
I'm also using Walton Primo GH6+ running android 6.0. It has a irritating battery drain problem and there is no automatic way to upgrade or downgrade your android. So you have to use a custom rom to get rid of it. I suggest you to use the Samsung S7 6.0.1 custom rom,it's the best custom rom for GH6 or 6+. It fixes battery drain problem,give it a try but MUST BACKUP your stock rom before.