Might be your batteries are shot. After awhile they just cant take a charge and you'll have to go with new set. If your still using the originals that came with the radio - 100% they are shot, those batteries came with the 396T were garbage, mine lasted six months or so.
I have bought energizer rechargeables at local stores mainly because I found em sale, Duracell would be good too. Dont go with a cheap non name brand in your expensive radio.
On here many swear by the Sony Eneloops brand.
I did find at Target
http://www.target.com/s?searchTerm=rechargeable&category=0%7CAll%7Cmatchallpartial%7Call+categories&lnk=snav_sbox_rechargeable
Try to get say higher MAH ratings ones, they'll last longer between charges.
Just on ALL radios there's no circuitry that senses the batteries are done charging on voltage, current. Even if the batteries are at 100%, plug in the power adapter and it starts a 14 hour charge timer.
Say after 14 hours, its done, unplug it from the wall adapter and plug back in, it starts the 14 hour timer yet again! Hard on batteries and they get warm.
The later version, 396XT you can set how many hours to charge. I set that setting at 2 or 3 usually.
I have charged mine for years no problems, just on your 396T be aware that unplug-plug back in will start that 14 hour timer again.
Side note:
I hope this thread isn't derailed too much by the charging in-out of the radio. The above comments by the others are correct though. Just a LOT of forums threads about charging batteries in-out of the radios on here and we have beat that to death.