HELP! Ryobi 14.4 Volt charger

I have a Ryobi 14.4 volt battery charger. When I try to charge one of the battery packs I get a Yellow and green light on steady at the same time. The directions on the charger says "See owners manual" The owners manual is long gone. Not available at Ryobi.com.
Directions for another model charger does not have the combo yellow-Green light steady on as a problem. Yellow and Red in that manual is a defective pack.
Any idea what the code means?
I'm going to guess the battery pack is defective. It is old and other packs charge fine.

It is a Ryobi 14.4 volt charger model 1412001

Dave, I had a couple Ryobi drills a few years ago. One of mine did the same thing. IIRC and I may not, getting old sucks, it was either an open or shorted cell in mine that triggered those lights. As I said, it's been some time ago but I do remember opening up the pack to find heat damage. I think I rebuilt it but I ended up just giving the set to my Dad afterward and replacing them with Porter-Cable 18 volt drills. Ryobi has a few gems, I still use my 1301 lunchbox with never a hicup, and those drills were one of them.