Battery goes dead after a few days the alt is good
Have the battery load tested,if good check both cables all the way to frame and starter.
I agree with Tst have your battery checked first. If the battery test good then you could have what's called a parasitic draw, which is any electrical component on the vehicle that stays on while the vehicle is off and stiting. This will require extensive electrical diagnostics and can be costly on the wallet.
Search Buick LeSabre Questions
Buick LeSabre Experts
Related Models For Sale