rooting - Unable to flash TWRP on a LG G4 (LG H815)

I own an international LG G4 LG H815 and running Ubuntu 14.04 LTS. For the whole day I am unable to flash TWRP on the phone. First I unlocked the bootloader with succes. Now I am trying to flash TWRP on the phone, commands that I used are :

mark@Mark-PC:~/Bureaublad/LG_G4_unlock/Root$ adb reboot bootloader
@Mark-PC:~/Bureaublad/LG_G4_unlock/Root$ sudo fastboot flash recovery twrp-2.8.6.0-hima.img 
target reported max download size of 536870912 bytes
sending 'recovery' (35928 KB)...
OKAY [  1.440s]
writing 'recovery'...
OKAY [  0.353s]

finished. total time: 1.793s

After flashing I immidiately turned of the phone by pulling out the battery to prevent normal booting. Every time I boot in the normal stock recovery that offers my to perform a factory reset.

I was reading the question flashing twrp on lg g4 no error, but no twrp but tries were also not succesfull. Chosing yes in the stock recovery wiped the data instead of booting to TWRP. I tried the same with different versions of TWRP for the LG H815 and of them gave the same result. My LG G4 is running Android 5.1 stock ROM without root.

I was also unable to find a file to flash by using fastboot that offers root access to flash a recovery from Android. All of the methods to root requires a working TWRP recovery.

mark@Mark-PC:~/Bureaublad/LG_G4_unlock/Root$ sudo fastboot boot twrp-2.8.6.0-hima.img 

Booting of the image directly did also not work

I will be very happy when I am able to salve this problem.

Now I tried this manual on another Windows laptop : https://techbeasts.com/2015/06/16/install-twrp-recovery-on-lg-g4-root-it/

but after the commands

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot boot recovery.img
downloading 'boot.img'...
OKAY [  0.710s]
booting...
OKAY [  0.400s]
finished. total time: 1.117s

unfortunately it boots normal after 20 seconds and stays unaffected.