Set everything to default.
Screen sill look bad?
FActory reset the phone...
1) Power off the phone
2) Hold down the '#'.
3) While holding '#', connect an AC adaptor to the phone.
4) Continue to hold '#' until the line buttons blink amber.
5) Release the '#' key.
7) The lights should change color from amber to red. The phone is now
resetting to factory defaults.
If you still have the problem you have a hardware issue for sure.
Please Kudos/rate if this help!
Are these new phones? If so, this may be due to the recent hardware change where the phones need to be on version 9.3.1SR1 or newer.