If you have the same problem, then reslove it as i suggested for rayan
otherwise you do not have the same problem...
If you have done everything as I suggested for him, and you still can´t turn the main switch on, then check the main reservoirs for air. You can´t turn the main switch on while on non-zero notch, and if you do not have enough air in reservoirs, you can´t notch down to zero. Then you must use emergency notch down function, tap down to zero notch and only after than you can turn the main switch ON. Of course, check for any additional air leakage, like emergency brake ventil is not opened, etc.
Emergency notch down function is available only when you´re stationary, in safe state (no main switch is on and no panto is raised) and you have non-zero notch (for example you´re on 7, check notch display for those). Keyboard shortcut should be Ctrl+Shift+I.
Here it is described in manual (no one reads that evidently)...