20 month naps I’m so frustrated

He still is napping twice a day usually because he sleeps like absolute garbage at night if I try to only give him one nap. But he is so difficult to get down down for his second nap because it’s a short wake window and it’s freaking frustrating. But no matter when I do one nap he sleeps like shit at night. I’ve been trying to get him down for his second nap for 40 minutes and he won’t go fall asleep even though he is definitely tired and his eyes are open and shut. What am I supposed to do