Wife bought a s7 and I have found it is running a custom firmware few questions.

About Phone : 64G Dual Sim Gold
Model number
SM-G930F
6.0.1
Baseband:G930FVPU1APB5
Kernel:3.10.72dpi@SWDD5616 #1 tue Jun7 19:53:44 CST 2016
Build:LRX22G.G930FZCU1AOD9
Custom build version: SEPF_SM_930F_5.0.2_0008
Phone INFO shows: Bootloader :Unknown
PDA Blank CSC Blank
Kernel Version:3.10.72 dpi@SWDD5616 #1 32-bit
Build Description: full_hexing6580_we_I-user 6.0.1 LMY471 1465299661 test-keys

My Questions are where is this firmware from, is it safe to use ?
Seems to burn through the battery fast.
Smart switch didn't work correctly, what could I try as alternative (Old phone is S5)
Is there a better custom firmware I could use?
Could this have been done to get around a blocked IMEI ?
Would it be safe to Flash a Stock firmware, will it still work, what firmware would I use ?
Location is Australia and Network is Telstra.
Thanks

Lost Video of my wife giving birth

hi all,
i came here with deeply desperate. i lost video of my wife giving birth.
it happened when i move videos from internal memory to external memory.
suddenly the files in external corrupted. the files name appears gibberish

there are two method i tried for the past 3 days
1. try to recovery from external (micro sd) using MiniTool Power Data Recovery, Wondershare Data Recovery, DRW. since i turned out that sd card have bad sector, the recovery progress stuck in 4%
2. try to recover directly from the phone. i also have issue with this method. since it requires me to the root the phone.
yes, without rooting i still can use software to discover lost data, but the softwares told me if it can discovery much more data if the phone is rooted) . unfortunately i cant find rooting method without flashing the rom. i dont want flash the rom , because if i do so im afraid the moved videos will be more difficult to recover. i also try once click root like framaroot, king root/ kingo root, Wondershare Dr.Fone for Android, none of them succeed rooting my phone (Lenovo Vibe P1 Turbo)

can anyone help me to recovery the file.
or please give me alternative how to root without flashing rom
thanks in advance