2008 RAM 1500 won’t start after sitting for a while

When truck sits a day or two it will not start. Will not even turn over without a charge.
New battery and terminals have been cleaned.
Any thoughts?

Yup, you have a parasitic drain. That means you have an electrical component in the truck that has an issue that causes it to draw way too much current even when the truck is off. If you have a) An aftermarket stereo - amps or radio or b) an aftermarket remote starter or c) an aftermarket alarm system, pull the fuse for those and see if the battery goes dead. If it doesn’t you have your cause. Replace the component or just leave the fuse out and live without it.

If you don’t have any of those 3, have your local mechanic run a parasitic draw test to find the problem part. You will have to pay for his time diagnosing it.