Unable to save parameters (reset on reboot)

I have problems with my pixhawk nearly like a post from joernsn.
But in my case in the QGC console I can’t execute “param reset” as result nsh: param: command not found

SD card seems to be working correctly lists the contents, and I can both create files and read them from a computer but with no bin. file under LOGS

Are you using Arducopter or PX4. .bin Logfile Extension points to Arducopter.

I am not sure that I understand what you mean.
In the QGC it will be detect as PX4.
The current firmware was only burned with the Mission Planner and not with the QGC.
On the SD card after I can not see a log file after operation in the APM folder.
In the QGC console I have a feedback but bye execute a command an error-message came as feedback as example nsh: param: command not found

That is what I meant. If you installed the Firmware using Mission Planer you have installed the Arducopter FlightStack.
The Command you are referring to is a PX4 (another FlighStack and what this Forum is about) Command. So it may or may not be available on Arducopter - in your case it is not.

Either check with Arducopter (Documentation or Community) or install PX4 Flightstack (using QGC and choosing PX4 when installing new Firmware).

APM = ArduCopter

Ok, now I have understood.
I have checked this with the PX4 Flight Stack and QGC.
SD card was new formated.
After selecting from the airframe the pixhawk start a reset but the selected airframe was not stored and is stil in red.
In the bootlog the PX4IO CRC was signet with OK.
He not save my parameters. Where will the parameters saved? In the STM or in the external onboard I2C storage.
I have seen that the time stamp in the log file is set to the 01.01.2000.
I assume it gave a RTC reset and what was also additional reseted?
The battery voltage are correct with 3.0V
I have no idea what can I do before I say the controller is scrap.

problem solved -
the SRAM - U102 - FM25V01 was faulty.

After replacing the SRAM the Pix can again storing values and after cold start readout.