I checked that flashing the V15 version vim3-u-aosp-v241101 might cause boot issues. You can flash the latest AOSP version instead.
20241220 Download Link:
https://dl.khadas.com/products/vim3/firmware/android/vim3-tablet-aosp-main-20241220.tar.gz
Instructions:
https://forum.khadas.com/t/vim3-vim3l-aosp-android-14-0-upside-down-cake/21192
Download and Operation Steps:
$ python3 boot-g12.py 20241220-vim3-tablet-aosp-main/u-boot_kvim3_ab.bin
$ fastboot oem format
$ fastboot flash bootloader 20241220-vim3-tablet-aosp-main/u-boot_kvim3_ab.bin
$ fastboot erase bootenv
$ fastboot reboot bootloader
$ cd 20241220-vim3-tablet-aosp-main/
$ fastboot flash boot_a boot.img && fastboot flash boot_b boot.img && fastboot flash super super.img && fastboot flash userdata userdata.img && fastboot flash dtbo_a dtbo-unsigned.img && fastboot flash dtbo_b dtbo-unsigned.img && fastboot erase misc && fastboot erase frp && fastboot format metadata
Press the R (Reset) button
$ fastboot reboot
Enter from the serial port：
setenv force_avb 1
saveenv
Operation video is as follows:
https://drive.google.com/file/d/16kFEJMg74sXEnHT4frAUKPyLvsbDNKec/view?usp=sharing