01 Kia Sportage 4x4 DEAD No start No power Needs jumpstart everytime

I turn the key – nothing – no power – no lights – no clock - completely dead.
The only way to get it started is to jump it.
After it is started it runs fine till I shut it off – then it goes completely dead – flatline
No matter if I shut it off for a long time or a short time - same thing.
No matter if its hot or cold - same thing - dead.

The battery is good
The alternator is good
The starter is good
Terminals are clean
Any ideas?

does the battery have a full charge ? whats the voltage and and amperage on the battery? battery voltage should be around 12.5 volts or more amperage will very on cold cranking amps and whats the voltage output of the altenater?and the amperage while at idle?

The battery is good
Terminals are clean
One of these is the problem....

Verify voltage at the battery posts ..then at the fuse block ...with light switch turned ON.

And..after you have boost started , measure voltage at battery post..the very battery post, not the connector..should read above 14 volts to prove alternator charges....and that amps are actually delivered to the battery. Corroded wiring occurs....