Samsung SPR6150 cordless Phone?

Hi,
I am hard of hearing and therefore use the speaker facility to help me hear.
Other members of the family use the phone.
The hand set has become faulty and will not hold the charge once the handset is lifted from the cradle.
I have fitted a new battery but when removing the handset from the cradle the display unit goes blank and will not work.
Are you able to assist me please?
Regards
Paul.