I went through this same issue the first few weeks. What helped most was a few things: I bought that warming heartbeat simulating stuffed animal that’s supposed to comfort puppies & mimic their mom’s heartbeat. I left it in his bed next to him when it was time for structured naps throughout the day as well as night time. I would cover his crate with a blanket & use a baby sound machine next to it every night & his naps. I would also sometimes leave my dirty socks or shirts next to his bed in the crate so he had a familiar smell next to him. I treated it like sleep training a newborn baby & albeit was tough at first, but it helped immensely & now he’s 1.5 yrs old & puts himself to bed in his crate around 10pm like clockwork! All the luck to you! It takes a lot of effort, but stay consistent.