CC2531 and ZigBee Binding, always in "unknown" state

ZigBee Binding is always in state “unknown”
What I’ve done so far.
Flashed the CC2531ZNP-Pro-Secure_Standard.hex
sudo ./cc-tool -e -w CC2531ZNP-Pro-Secure_Standard.hex
Programmer: CC Debugger
Target: CC2531
Erasing flash…
Writing flash (241 KB)…
Completed (18.10 s.)

sha256sum CC2531ZNP-Pro-Secure_Standard.hex
3cc5dc571ef0f49e3f42c6c2ca076d6f8fef33a945c71e6f951b839ba0599d3c CC2531ZNP-Pro-Secure_Standard.hex

In /etc/default/openhab2
I have
then I did a sudo /etc/init.d/openhab2 restart

Also I did
sudo adduser openhab dialout
sudo adduser openhab tty

and (not necessarly anymore)

sudo chmod 777 /dev/ttyACM0

Then I added via Inbox --> „+“ --> Zigbee Binding --> Add manually --> CC2531EMK Coordinator

State is now unknown

Also I can’t select channel 26, only channel 25 as maximum. Why?

I’ve also tried 38400, also no success

I would suggest to check the debug logs. Please read the documentation for enabling debug logging - in the section When things don't appear to be working.

Problem solved. Error was that on RaspberryPI /dev/ttyAMA0 is the internal serial connection. You have to use /dev/ttyACM0

Error message without changing loglevel to debug was

2019-06-21 21:04:59.315 [WARN ] [] - Dongle reset failed. Assuming bootloader is running and sending magic byte 0xef.
2019-06-21 21:05:04.317 [WARN ] [] - Attempt to get out from bootloader failed.

Hey Together,
i piced this thread, cause I dont want to open another one :-).
Yesterday I updated to OH 2.5.3-1 and everything seemed ok.
Today I wanted do clean cache (sudo openhab-cli…) and ofter a restart, I have exactly this problem.
The thing is when I change from ACM0 to AMA0 nothing happens and after a reboot ACM0 ist selected again.

Dongle reset failed. Assuming bootloader is running and sending magic byte 0xef.

now I get back an archive (just restore cli-console 2.5.3) bevore celaning cache and everything works fine but with ACM0 selcted.

Anybody any Idea, cause it is not that stable when I cannot clean cache within the future.