HELP ! Ramdisk error 6S ios 15.4.1

[sirham]

i always get this error when trying to boot Ramdisk 6s ios 15.4.1

BOOT RAMDISK Checking for device... OK
Info : iPhone 6s [iPhone8,1-n71ap]
Boot : [IBOOT-2234.0.0.3.3] [DFU]
Pwnder : GASTER
Initializing... OK
Sending ibss.img4... OK
Sending ibec.img4... FAIL
ERROR: Unable to connect to device
Tips : If device keeps booting up while sending ibss or ibec
Press and Hold VOLUME DOWN + POWER while sending ibss and ibec
After done sending ibss and ibec you can release those buttons.
UNLOCKTOOL 2023.08.18.0
Elapsed time : 44 seconds


i hold the buttons but no success

 

[Phu Mobile]

hold down the power button for 2-4 seconds and the download will continue