Fastboot is a method to quickly upgrade each partition package of Android.

You can follow install adb tool to install fastboot tool.

1. Connect the PC host and board with USB cable.
2. Refer the documentation ( VIM1/2/3/3L/4/1S/Edge1 / Edge2 ) to setup your serial tool.
3. Once again, make sure you've done the correct connections and setup.
4. Hit Enter keys at the moment of bootup to stop autoboot. This step will let the board boot into U-Boot Mode.
5. Type fastboot 1 command to enter the burning mode.

kvim1s# fastboot 1
PHY2=00000000fe03a020,phy-base=0xfe03e000
serial num: 0000000000
crg_udc_epcx_update_dqptr Cannot update dqptr for ep0

To use fastboot to flash the machine, you must first unlock the bootloader, otherwise the machine cannot be flashed.

After entering the fastboot mode, run the following command to unlock:

$ fastboot flashing unlock
$ fastboot flashing unlock_critical

C:\Users\25348>fastboot flashing unlock
...
OKAY [  0.372s]
finished. total time: 0.377s
 
C:\Users\25348>fastboot flashing unlock_critical
...
OKAY [  0.007s]
finished. total time: 0.009s
 
C:\Users\25348>

$ fastboot devices
$ fastboot reboot
$ fastboot reboot-bootloader
$ fastboot flashing unlock_critical
$ fastboot flashing unlock
$ fastboot flashing lock_critical
$ fastboot flashing lock
$ fastboot flashing get_unlock_ability
$ fastboot flash bootloader bootloader.img
$ fastboot flash bootloader-boot0 bootloader.img
$ fastboot flash bootloader-boot1 bootloader.img
$ fastboot flash dts dt.img
$ fastboot flash dtbo dtbo.img
$ fastboot flash vbmeta vbmeta.img
$ fastboot flash logo logo.img
$ fastboot flash boot boot.img
$ fastboot flash super super.img        # not support burn logic partition in bootloader
$ fastboot flash recovery recovery.img
$ fastboot erase env/param/tee/boot/recovery/dtb
$ fastboot -w
$ fastboot format cache
$ fastboot getvar all
$ fastboot getvar is-userspace          # return no in bootloader
$ fastboot getvar is-logical:boot       # return no, others
$ fastboot getvar is-logical:system     # return yes, system/odm/vendor/product
$ fastboot getvar super-partition-name  # return super

$ fastboot flash vendor_boot /path/to/vendor_boot.img

$ fastboot flash vendor_boot_a /path/to/vendor_boot.img

$ fastboot reboot

Fastboot .