It sounds like you've been inconsistent in your approach to his sleep (correct me if I'm wrong) and he's confused and doesn't feel safe in his cot as a result. He has probably also made the connection that if he cries for long enough, you will come.
I think all these methods can get in the way of parental empathy and common sense. Try to imagine it from his point of view, making sense of what you want from him and how this cot business works. Babies (like all of us) rouse slightly between sleep cycles, check out their surroundings, then hopefully drop off again. If there's something there that he doesn't like, or he's bizarrely (from his point of view) moved from where he was when last awake, he's going to be afraid, wake up fully, and yell.
A baby is much more likely to sleep happily in their cot if they feel safe, and imo that is a consequence of you always going to them when they need. I think the idea that if you go to them when they cry, will make them cry for you more, is nonsense. My experience with DD has been the opposite.
If you agree with that...... You need to work hard to make him feel ok again there. The daytime naps are positive. In the evening, get him calm, sleepy and relaxed - always the same routine in the same place. In the room you want him to sleep in is a good idea. Stories, singing and rocking with low light. If you have a nightlight that you can then leave on for the first few nights, so much the better. (Ikea does a great plug in one). Take him to the cot while sleepy and awake. Put him down. If he cries, pick him up and cuddle him til calm and relaxed. Repeat. Stay until he's asleep (as time goes on, you'll need to do this less). If he wakes up and cries you need to go back and comfort him immediately. This is not pick up put down.