This device is easy to use. 1). Connect it to a computer by the USB cable. 2). Insert the keyboard cable into the corresponding connector. 3). Push the opening button, the device will sound 2 times, which means it starts working. 4). Press keys of the keyboard, if every keys sound, it means the keyboard is good, if not, the keyboard has problem. If the sound is long and can not stop, the keyboard might be bad or the cable is not installed correctly or firmly. 3. who to use: I recommend this device to laptop keyboard dealers like keyboard seller, retailer and wholeseller. I use it myself to test keyboards when needed. Sometimes we buy keyboards but which look not very good, or there might be some signs of damage on it, then I will test the keyboard by this tool. And sometimes, we got keyboards which look brand new but customers said they don't work correctly, I will test some of our stock to check. From my experience, it will be very helpful when you have doubt over your stock but you don't have a laptop to test the keyboard. Once you find the problem, you can stop selling and communicate with supplier to resolve the problem. From my own experience, this device saved a lot of money for me. I love it very much !!! Note: 1- It Can't test the pointer in every Laptop Keyboard 2- it can't test Thinkpad X300 ect keyboard which have very special FPC or no FPC. 3- It can't provide all suitable connectors for all laptop keyboards. For example, it cannot test keyboards with 0.5mm pitch FPC 4- It can't test three keys on LENOVO IBM THINKPAD Keyboard, whose function is the same as Right , Left and Middle Key on Mouse. 5-Installing your Connector, please be carfully. thanks