I have noticed this mark before, but I found that channels 1, 4 and 6 have marks, but after the update, the mark on channel 1 disappeared, and other channels have not seen the mark for the time being. What is the input method of this password and how many marks are there?
Viewing post in Surveillance Simulator comments
On the right wall of Line 4, there is a marker. Additionally, a marker can be found in Line 6. The marker actually exists in Line 1 as well, but it's not visible. The last marker is on Line 9, but it's not within the surveillance. Instead, it's on a cabinet in the control room. At this point, two possible passwords can be obtained: 4169 or 4119. Enter each of these sets of numbers on the controller and then press the power button to activate the surveillance; one of these sets is correct.