Battery light stays on

Fully charge the battery and have it load tested. with the engine running you should have over 14 volts on a multimeter. if you don't, your new alternator is bad. happens a lot. that said, check your battery cable connections and make sure they are clean and tight on both ends. wouldn't hurt to scan the computer for codes while you are at it. If all of that checks out, there are good YouTube videos on how to find a parasitic draw in your car. will require the use of a multimeter tho.