My Gameboy won't charge even after replacing the batter :(

I recently found my old gameboy advance sp that I have had since 2005. I bought a charger for it but when I plugged it in the GBA the charging light flashes for a second then turns off. After a lot of googling I figured it was a battery problem so I bought a battery replacement for the GBA but, it’s still doing the same thing. I have no idea what to do now and really need help. SOS :(