Walls have huge electric fields (thousands of V/m)

I live in an old apartment complex in Minnesota. I measured the EMF in my walls and in the walls of a neighbor whose unit is very far from mine. In both cases, even with no appliances plugged in at all (other than the refrigerator) the EFs range from hundreds to thousands of V/m. Even setting all the circuit breakers to Off only partly lowers them. They are still hundreds of V/m even with all circuit breakers off. The magnetic fields are also much higher than 1 mG when I place the meter on the walls.

The Stetzerizer Microsurge meter shows every outlet is from several hundred to two thousand. I bought 14 Stetzerizer filters and placed them all over my apartment, including in the many outlets where nothing is plugged. While I can get the Stetzerizer meter value down considerably, the electric and magnetic fields at the walls are unchanged, even without a single appliance plugged in.

I don't know what to do, the managers of my apartment complex ignored every request to send a competent electrician. I even tried making a video of the meters but they dismiss the problem, ignoring my messages. Do these EMF values mean wiring errors? Do I have any legal power to have the apartment complex fix those? I had a young cat drop dead without apparent reason in my apartment and my neighbor had a young rabbit. At night we sometimes hear a sizzling noise like standing under power lines, however the power lines are not close to the apartment complex. Something seems very wrong with the walls. I measured the EMF at work and at my gym and the walls are only few V/m at most.

Thank you so much in advance for any suggestions!