Late in the game, you’ll come across an item called the Signal Modulator in Resident Evil 2.
You’ll need to use it in order to restore power to certain areas of the location you’ve found yourself in, but might be at a loss as to how to do so. The game doesn’t really explain it, after all.
To use the Signal Modulator, examine it in your inventory. You then need to use the left and right bumper buttons on a PS4 or Xbox One controller to match the word at the top of the device with the panel you’re wanting to activate, which will change the frequency shape on the Signal Modulator’s display panel.
Once the word has been matched between the panel and the Signal Modulator, you need to move the left and right analogue sticks so that the solid and dotted wavy lines also match. Then, you can walk up to the panel you wish to use the Signal Modulator in, insert it, and power will be restored. You’ll find that there are about three panels that the Signal Modulator can be used on in Resident Evil 2.