u/Inevitable_Coat_2071

I bought a 2003 dodge ram with 150k miles on it a couple months ago, it ran great for a couple weeks then one day the security light started blinking and it wouldn't start, I bought a new battery and it ran for a few more weeks then same thing then bought a new alternator and also changed out the positive battery terminal connector because it was corroded, got it to start then next day it wouldn't start again. Can anyone explain what's wrong?

I bought a truck it ran for about a week then it went into security theft mode and wouldn't start, I bought a new battery and it ran fine for a couple weeks then it put me back into the security theft mode, got new alternator and changed out the positive battery terminal because it was corroded, jumped it it started then the next day it didn't want to start again. Can anyone explain what's wrong?