Fail to change the state of rfkill

Hi,

Everytime I change the value by the way “echo 0 > /var/lib/systemd/rfkill/platform-481a6000.serial:bluetooth”, then it works. but when I reboot the system, the value will be reset to 1.
I wonder why it always happen, and how I can enable the bluetooth automatically as the system is ready.
Could you please help me?
My device is Beagleboneblack wireless.

git:/opt/scripts/:[38ce81fcdafad0892b6c485acd4e9a2245dfb07a]
eeprom:[A335BNLTBWA51905BBWG0309]
model:[TI_AM335x_BeagleBone_Black_Wireless]
bootloader:[eMMC-(default)]:[/dev/mmcblk1]:[U-Boot 2019.01-dirty]:[location: dd MBR]
kernel:[4.9.146-bone-rt-r12]
uboot_overlay_options:[disable_uboot_overlay_video=1]
uboot_overlay_options:[disable_uboot_overlay_audio=1]
uboot_overlay_options:[disable_uboot_overlay_adc=1]
uboot_overlay_options:[enable_uboot_overlays=1 ]
pkg check: to individually upgrade run: [sudo apt install --only-upgrade ]
pkg:[bb-cape-overlays]:[4.4.20190404.0-0rcnee0~stretch+20190404]
pkg:[bb-wl18xx-firmware]:[1.20190227.1-0rcnee0~stretch+20190227]
pkg:[kmod]:[23-2rcnee1~stretch+20171005]
pkg:[librobotcontrol]:[1.0.4-git20190227.1-0rcnee0~stretch+20190327]
pkg:[firmware-ti-connectivity]:[20180825+dfsg-1rcnee1~stretch+20181217]
groups:[debian : debian adm kmem dialout cdrom floppy audio dip video plugdev users systemd-journal i2c netdev gpio pwm eqep bluetooth admin spi tisdk weston-launch xenomai cloud9ide]
cmdline:[console=ttyO0,115200n8 quiet lpj=1990656 root=UUID=ae512078-9e1b-47e2-97e7-8b462d4c8756 ro rootfstype=ext4 rootwait]
dmesg | grep pinctrl-single
[ 2.368289] pinctrl-single 44e10800.pinmux: 142 pins at pa f9e10800 size 568
dmesg | grep gpio-of-helper

We also fight this in the default debian images, i haven’t discovered what forces it to default to 1…

Regards,