Vtech 8L55 2 unit portable phone

I had one set of batteries on one set quit holding a charge. I put in 3 new batteries and put it back in its cradle charger. It said it was charging..then shortly it said it was searching. Then it started beeping. I left it on the charger overnight and it still will not work. I took batteries out of the good handset and put in it and it still does the same thing. The one I took the batteries out of started doing the same thing once the good batteries were replaced. It started working again on its own. Any ideas? Thanks John