Well well you managed to figure out how to engage the sonar sensors, now you'll hear a slightly annoying beeping sequence from the box. I wanted this beep to sound just right and I consulted my assortment of salvaged noisemakers:

After some time you should realize that this is Morse code and if you are not a hardcore HAM-radio person or similar it is up to you to find a cheat sheet for morse code and decipher the 5 letters. (Spoiler Alert - it says LASER).