My keyboard was no longer in use for few months. Now I need to use this keyboard, It's showing it's power on light and it’s blinking. It's also discoverable to connect but no keys are working I am not able to pair because it ask to enter a pin and keys are not working neither numpad nor numeric keys. Also, Caps lock light, Numlock lights are not working. Do you have any idea if I tear down to investigate, what should I clean/check? Please respond I really need to use this keyboard for now.

Thanks in advance.