Question about my Sega Game Gear. Need help.

I am selling my Sega Game Gear for money to go to my Gameboy SP fund and I have a question: Do I just plug the travel battery pack in to charge it? Do I flip the switch to on or off for charging? Because after all last night I charged it and the battery seems dead. Just want to make sure so I can change my auction on Ebay.

By the way , I took my super nintendo and 12 games to Gamestop over the weekend and got $45 credit. Too bad they have not had an SP in stock in 3 weeks

After this long it could be the battery is just dead. What kind of battery is it? A nickle hydrate?

I am guessing it may be dead even though I can get the power light on it to flash just by switching the switch on and off. But it only stays on for a split second.

I will check to see what kind of battery it is when I get home from work. It can''t be a very good one