Step 1    Download official flyme ROM of your phone
Step 2    Boot into recovery mode (off your phone then press ("on + vol up" same time)
                  after that it will show" update" and "clear data"option.
                                            Then
Step 3    Connect the device to window PC/tablet(if driver are installing let them complete)
Step 4     A new drive will show in system copy ROM zip into that drive
Step 5    Disconnect the phone from the PC and choose "update + clear data"(necessary)
                 after that starting flashing ROM
    First boot always take time SO don't  PANIC


Note  phone with  only original recovery works ( modify or third party recovery not work e.g twrp, cm ,cwm)

Note 1 the  internal memory will not erased all the files song multimedia video  ..etc all are present.
Note 2 flashing ROM will take time up-to 20 to 30 min or less SO don't  PANIC .

hit like or thumps up if helped