It sounds like you’re referring to the — likely a specific diagnostic or functional test for a keyboard switch, particularly one with an Aqua (light blue/green) colored stem, such as Aqua Zilent or another custom mechanical switch.
Want a printable checklist version of the Aqua Key Test? I can make one. Or if you meant a different “aqua key test” (water immersion test for keycaps or waterproof keyboards), let me know and I’ll write that instead. aqua key test