OK, since it will not power up with known good alkalines, and also it never offered to charge batteries, when using an adapter with enough output to both charge and run the scanner, then this may be a repair issue. If you purchased it new, then unless damaged (which does not seem to be the case), repair would be covered by the warranty. Uniden's servers are currently down, and are not projected to be back up before Tuesday at the earliest. Their office is moving. But, once they are back up, start your repair request here:
Repair rates
Usually, for in-warranty repair, they will want a copy of your proof of purchase, to validate coverage under the one year warranty. If you purchased it used, you can find the rates for repair on that same page. There is a form to fill out with details of the problem, and generally, they advise to not ship it with the batteries, the memory cord, or antenna.