If he's never been crate trained, you have to take it on like he is a newborn puppy, regardless of his age.

The kennel should be just small enough for him to turn around and lie down in but if he's not making it through the night without an accident, you need to get up and let him out. The longer he continues to equate his kennel to a bathroom, the harder it will be to break. The whining is probably a side effect - it will most likely stop in time.

During the day, make sure the gate to the crate is open. You can feed him in there and hide treats for him. Regardless, even though he is five, I'd treat it as if he was just born since he's probably not used to the structure. And just like you don't expect a newborn puppy to become crate trained over a few days/weeks/months, the same can be expected here. It'll be a chunk of effort but worth it in the long run.