I've unlocked with htcdev everything is fine.
Then I installed Twrp-220.127.116.11.img as recovery.
I'm not able to mount the internal storage, so I had to push the ROMs via ADB.
starting a ROM 1st time seems to be ok.
restart is also ok.
shutdown and power on is rebooting every ~15sec.
I tried to change my bootloader with ADB.
fastboot flash recovery recovery-clockwork-touch-18.104.22.168-m7ul.img -> volume keys are responding
fastboot boot recovery-clockwork-touch-22.214.171.124-m7ul.img -> volume keys are NOT responding
recovery isn't starting until i run following commands:
fastboot flash recovery Twrp-126.96.36.199.img -> volume keys are responding
fastboot boot Twrp-188.8.131.52.img -> volume keys are NOT responding
but after resetting the device + entering recovery it's there
thanks for your ideas/help