To summarize, I have a light on a 3 way switch that will not go off via the switches. I replaced both switches with new 3 way switches and the light still won't go off.

We have a hall light that has one switch upstairs and one switch downstairs. The light won't go off so I changed the switches and replaced the old switches with new 3-way switches on both ends.

On the upstairs switch, were two black wires (old ones with a cloth type insulation) and one black wire with plastic insulation. The black plastic covered wire was on a black screw and the cloth covered wires were on brass colored screws on the old switch. I put the black plastic covered wire onto the black screw on the new switch, and the two old cloth covered wires onto the two brass screws on the switch.

Downstairs, there were two black wires and one white wire. The white one was connected to the black screw so I assumed it was the live wire and connected that one to the black screw on the new switch, and the two black wires I connected to the two brass screws on the new switch.

Thinking I was all done, I switched the power back on and the light still stays on all the time, even after turning the light switches off. I don't know much about wiring, but I had assumed that all power to the light would be cut off if a working switch is turned off.

The only thing I can think of is that one of the new switches I bought is also broken, but that seems so unlikely. Any other suggestions on how to troubleshoot this issue?