Cordless phone won't charge handset battery

[F117NightHawk]

I bought a Siemens 2415 2.4 GHz cordless phone on Friday and so far, the handset hasn't charged the batteries at all. Sometimes the battery indicator will show that it's almost at full power, but then I'll look a second later and it's back down to almos empty. I've left it for 12 hours like the manual says, but if the handset's off the base for more than 30 sec. it goes blank. I called their tech support and the tech had me unplug the base and take out the batteries to "reboot" the phone. I'm hopeful that this will do something. Has anyone ever had this experience with a cordless phone?