My bird hates the cage. Help!

Hello!
I have a 5 months old Indian Ring Neck.
I have bought him when he was 3 months old, so I have him for 2 months now.
I kept him in the cage a week and a few days before letting him out of the cage, so he can get used to the environment and room.
When he finally got out of the cage, he didn't wanted to go back at all.
I had to catch him a few days so he can get in. Later, I made him go back in the cage using one of his favorite food, but now he doesn't want to go back for nothing in the world.
He was out for a month without even going back for 5 minutes in the cage. Not even for his favorite food... (Corn)
Luckily I'm home all day long, so I could watch him.

Now I'm at my parents house for a week now, and I'm afraid to let him out. There are a lot of plants around, and there are days when I need to leave home, and I'm afraid to let him out alone without anyone to watch him.... And I'm gonna stay here a few months. I can't keep him inside that much...

I want to let him out, because I pity him, and I also know he needs to exercise.
What can I do make him get used to the cage, get inside, and like the cage?
Is the cage too small? 24 x 16 x 35,5 ( L x W x H )?
He has toys in it, food, and everything he loves and likes.

Please help!

Does he step up at all? If not, you probably need to work on that first. The current issue of Bird Talk has two good pieces, one by Barbara Heidenreich and one by Sally Blanchard, that touch on getting birds to go back in their cages. Both individuals are bird trainers, and have books available on behavior training for parrots.

One tip I gleaned: always make sure there's a plus to going back in the cage, as most birds would rather stay outside their cage. Put in a new toy, or find a favorite treat (which it sounds like you've tried). Maybe you need to use that treat only when trying to get your bird back in his cage, or maybe you need to find another motivator.

Either way, there are tools out there that might help, so check you local library, or look for articles online by the two authors mentioned above.

Links:

https://companionparrotonline.com/index_QNU6.php

Good Bird Inc Parrot Training Talk

Good luck

Like bright star said, make sure he has learned "step up" first. I would also be more consistant with the time he is in and out. Have a set time in the day when comes out and goes in and reward with treat when he goes back in. This worked for my lovebirds I had in the past, after a while they would go back with out me having to do anything around that time. I would let them out from 6 to 8 in the morning and 5 to 10 at night.

yes like everyone said teach him that step move!