I feel your pain... my 5.5 month old has been a real challenge when it comes to sleeping. I’ve found persistence and consistency has been really helpful for the day naps. If she wakes up before 6:30, I resettle her in her cot with a dummy or in bed with me until 7am. Then I open the curtains and start the day. This never changes and she has got used to starting the day in this way. She then naps every 2 hours, and her first two naps are always in her cot with curtains closed again and white noise. She used to cry her eyes out when I put her down but by always following the same routine and following the sleep reassurance techniques, she now starts telling me she’s tired and goes off to sleep with very little fuss. I would say don’t be afraid to let him cry a bit, but obviously never let him get too worked up. I never let the crying go on more than 45 mins and will pop in at varying intervals whilst it is going on if I feel the crying is getting too intense and out my hand in her chest and tell her it’s sleepy time. It is hard to listen to your baby crying, but eventually they do sleep, and feel reassured by the routine and knowledge you will always be there when they need you. I’m still struggling to get her to sleep through the night but it’s improved a lot since we cracked the day sleep. Also gives me more time to have a break and the occasional nap too. Good luck, I know it’s exhausting but you will get there.