Help, do not know position of valve. Vaillant

Hello guys, I have one question. Should this valve stay open or closed on my vaillant turbomax boiler? I had fiddled with it because I had low pressure after removing air from one heater. Now I do not know correct position. Like this _ or other way I?
https://ibb.co/X3Wm1tK
With it the other way the boiler started flashing from led no 5 and stopped heating
https://ibb.co/tm76n2j
Also is the pressure too high?
I am new at this boiler stuff, I just moved to new apartment and I need some schooling.

That should be across the pipe to be off,it’s in the on position at present ,only turn on to top up pressure

Pressure's spot on. Any (ball) valve usually needs to be at 90deg to the run of the valve to be in the off position, slot should be the same.

I was thinking should be like that. I don't know why was giving alarm last night. I closed it thanks for the answer guys. I appreciate it!