cwd 2900 handsets wont work?

I replaced the re-chargeable batteries in my CWD 2900 and cwd 285 handsets and they wont work. They are part of a network with 3 other NTL d505 handsets. They have been working fine for 2-3 years, but I started getting funny beeping, so I decided to replace all the re-chargeable batteries in the handsets. The ntl d505 handsets are fine and the system still works from the cwd 2900 base station, just the two CWD handsets do not. Cant find instruction booklet anymore.
Anyone Help?