Prepare your system-----
1) Install the Qualcomm usb drivers on your system. Download link
2) Check your PC device manager, your phone should be detected in "Qualcomm HS-USB QDloader 9008" mode. It must detect to start the process.
3) Download the stock firmware from here
. The software version downloaded with this link is "LS-5201-S10A_LYF_L13EN_200_170124_09-55-13".
4) Extract the downloaded firmware zip to an folder and rename the "IMAGES_FOR_QMSCT" to "firmware".
5) Download & install the QPST tool. Google it you can find it easily.
6) power off your phone & Make sure your device is charged to at least 50%.
7) Run the installed QFIL from installed programmes. Browse in programmer path to the "prog_emmc_firehose_8976_ddr.mbn" file in the folder where firmware is extracted. It will load the firmware & buid will be selected automatically.
8) Click on load xml and select the "rawprogram_unsparse_without_qcn.xml" if you havn't the backup of NV partition of your device.
If you have the backup NV partition of your device than you can select "rawprogram_unsparse.xml" because this will erase your RF Calibration data, IMEI and WiFi/Bluetooth Address etc. and you will have to restore the NV partition after installing the ROM.
I would suggest you to select "rawprogram_unsparse_without_qcn.xml" & keep it simple.
9) Choose the "patch0.xml" after that.
10) Hold the vol+ & vol- key together and plug usb cable to phone to enter into download mode. As you plug in the QPST tool would recognise your device in QDLoader 9008 mode with com port no. and download button will get activated.
11) Click the download button and sit back, it will take some time.
12) "finish dowload" appear, when process got completed and phone will reboot automatically.
13) Disconnect the device from PC one "android screen" appears (usually it takes 5 min. to appear LYF logo screen from android boot screen)
14) If doesn't reboots, there is some problem & get ready for real hard work
You might have bricked. In this case just press the power button so than it can power ON. If android screen appears you are lucky enough
-----If android screen remains more than 6-8 minute, you are in bootloop. (It useually takes 5 min for LYF logo to appear after android logo)
-----To switch off your device in case of bootloop, press vol+, vol- & power key together for some time. It will switch off.
-----try to flash the firmware again by above process.
I have tested this method on my device and successfully flashed the stock firmware.
Don't forget to "HIT thanks"...!!!
for providing the stock firmware
: for testing the procedure