Hi, thank you for contacting JustAnswer.com. My name is***** will do my best to provide the right answer to your question.
It may be that the phone is 'broken', from the sound of it.
I suggest that you unplug the phone from the line, and from the power.
And take the battery out of every handset for the phone, also, after turning all the cordless handsets OFF.
And leave the whole phone that way for at least 20 minutes.
Then plug in the phone's base unit to the power. And to the phone line.
Then put batteries back in the handsets, and turn them on, one by one, with 15 seconds between each turning on of the handsets.
See whether that cures the problem. It is does not, you may, unfortunately, have a defective phone.