Detecting Cable Faults in Plasterboard Renovation: Phase on Neutral Issue

Hello. I'm doing a renovation. I put plasterboards on the profiles and in the middle I let the cables with electricity. Everything is ok, only one cable had to be screwed in because the light bulb flashes when I turn off the switch. besides, when this cable is turned on, in the sockets I have a phase on the ground and also on zero. How can I check where I got tangled in the cable?
I have the light and sockets on separate eskas. The phase on neutral and Pe is in the switchgear as this cable with breakdown is turned on.

Spelling - correct!
[Acres]

It shows that you have found the wire between the switch and the box and you need to look for it there. If you routed the wires in a bundle, you may have injured the adjacent wires by the way and maybe the phase on the protective contact has appeared. If you have a lighting box available, first look well and x-ray the switch, there may be a damage there. If not there, you need to remove one central board and remove the damage. Alternatively, check the power supply from the switchgear to the first box to be sure, but this is probably not the problem. Disconnect the socket's power cord completely (three wires) and see if the phase from the lighting circuit to the protective contact of the sockets does not pass. Do the same with the lighting circuit, and then you will see what wire is damaged.

Something is wrong here, like the phase on the protective contacts? Unless with the cable powering these sockets unplugged from the switchgear? Ew. the continuity of the PE wire has been broken, because any contact of the phase directly with N or PE should cause a short-circuit and trip the fuse.

As for looking for the fault, you can try some sensitive voltage detector (e.g. phaser 777, a yellow screwdriver, you can buy at the supermarket). Turn on the detection to the max and touch the tip of the wall to find the place where the insulation is broken, or trace the cable route. But it doesn't always work, although with one layer of GK it should.

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the bulb flashes as the switch is turned off

Hello.Flashes often? Tell me what bulb it is. If you have a fluorescent lamp, do you have an illuminated switch?

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The phase on neutral and Pe is up to the switchgear as this cable with breakdown is turned on.

Do you measure on the strip or disconnect for N and PE measurement. What are you measuring with? Can you measure insulation resistance?
Think over

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Something is wrong here, like the phase on the protective contacts? Unless with the cable powering these sockets unplugged from the switchgear? Ew. the continuity of the PE wire has been broken, because any contact of the phase directly with N or PE should cause a short-circuit and trip the fuse.

I will explain more extensively:
I have a light switch. Recently, the bulb started flashing for me - I disconnected the backlight and it helped. Later, it flooded my floor and started flashing again (40 W energy-saving bulb). In addition, electricity was felt in the water on the ground (the water was in contact with the profiles at the very ground). I have separate eski for light and sockets. When this light bulb was blinking, in the next room (but connected with the same ESCs) a neon light was shining in the socket for N and PE. in the switching station on the N-rail, a neon lamp glowed softly. After turning off the cable from the flashing light bulb, everything returns to normal. Already the water on the ground has dried up and everything is ok. nothing flashes. I just need to fix it for the future. I don't have a differential connected in the switchgear yet.

I think you have a babola in the switchboard. How can even trace phase indication be visible on the N and PE bus. I advise you to check the connections and absolutely insert a differential, because with this flooding and punctures it can end badly.