My 2005 Gs 300 my battery is draining

Sounds like a you have a parasitic draw. This is when an electrical component fails internally and will stay awake even whey the car is off. This issue require electrical testing to determine where the drain is coming from. Here is a link to find a show near you. https://repairpal.com/repair-shops Alex

https://www.youtube.com/watch?v=zdIKNnwEjIs

I see the alternator was replaced - is the new alternator properly charging the battery ? After dark - see any lights on inside car ? .. Take video with phone to see if trunk light is turning off when lid is closed .. Look at *ALL* interior lighting to be sure nothing is staying on. Any aftermarket add-on accessories ? .. ALL of the power door locks working properly ?