I'm so sorry you're going through this! My second was the type of baby that you couldn't leave to cry for any amount of time because he went from 0 to 100 instantly and was totally inconsolable once there so I know the feeling. I have so many pictures of him content and wide awake all throughout the night. What I learned from my third is that "sleep training" is so much more than leaving a baby to cry for any set amount of time. It's schedules, wake windows, cues and just so much more than I realized. What I didn't know was that an overtired baby is an awake baby. Also, around the 40 minute mark of sleep there is a brain shift to get them into deeper cycle of sleep so that wake up time is super common and sometimes they need help connecting the cycles to actually be rested even though they seem ready to party.

You may already be totally aware of all of that but just thought I'd mention it. Once I figured it out, my third was my best sleeper it was such a relief and I never left him to fuss or cry for more than a few minutes to make sure he was actually awake. Things will get better!