install openwrt to nand on bpi r3. without having access to uboot by serial

nand_install.sh

# bpi r3 openwrt install to nand
# boot from sd, switch 1111
# dev:    size   erasesize  name
# mtd0: 07e00000 00020000 "ubi"
# mtd1: 00200000 00020000 "bl2"

insmod mtd-rw i_want_a_brick=1
wget https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/openwrt-mediatek-filogic-bananapi_bpi-r3-snand-preloader.bin
mtd erase bl2
mtd write openwrt-mediatek-filogic-bananapi_bpi-r3-snand-preloader.bin bl2
ubidetach -d 0
mtd erase ubi
ubiformat /dev/mtd0
ubiattach -m 0
ubimkvol /dev/ubi0 -N fip -s 0x200000 -t static
wget https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/openwrt-mediatek-filogic-bananapi_bpi-r3-snand-bl31-uboot.fip
ubiupdatevol /dev/ubi0_0 openwrt-mediatek-filogic-bananapi_bpi-r3-snand-bl31-uboot.fip
wget https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/openwrt-mediatek-filogic-bananapi_bpi-r3-initramfs-recovery.itb
ubimkvol /dev/ubi0 -N recovery -s $(du -b openwrt-mediatek-filogic-bananapi_bpi-r3-initramfs-recovery.itb|awk '{print $1}')
ubiupdatevol /dev/ubi0_1 openwrt-mediatek-filogic-bananapi_bpi-r3-initramfs-recovery.itb
wget https://downloads.openwrt.org/snapshots/targets/mediatek/filogic/openwrt-mediatek-filogic-bananapi_bpi-r3-squashfs-sysupgrade.itb
ubimkvol /dev/ubi0 -N fit -s $(du -b openwrt-mediatek-filogic-bananapi_bpi-r3-squashfs-sysupgrade.itb|awk '{print $1}')
ubiupdatevol /dev/ubi0_2 openwrt-mediatek-filogic-bananapi_bpi-r3-squashfs-sysupgrade.itb

# Volume ID:   0 (on ubi0)
# Type:        static
# Alignment:   1
# Size:        17 LEBs (2158592 bytes, 2.0 MiB)
# Data bytes:  1109993 bytes (1.0 MiB)
# State:       OK
# Name:        fip
# Character device major/minor: 250:1
# -----------------------------------
# Volume ID:   1 (on ubi0)
# Type:        dynamic
# Alignment:   1
# Size:        74 LEBs (9396224 bytes, 8.9 MiB)
# State:       OK
# Name:        recovery
# Character device major/minor: 250:2
# -----------------------------------
# Volume ID:   2 (on ubi0)
# Type:        dynamic
# Alignment:   1
# Size:        93 LEBs (11808768 bytes, 11.2 MiB)
# State:       OK
# Name:        fit
# Character device major/minor: 250:3