Raspberry pi not booting after update

I updated my raspberry pi 4 using the command:
sudo apt update && sudo apt upgrade
but after that my raspberry pi is not booting
I have put that card in my raspberry pi 3 and it is working fine but my pi 4 is not
I have tried replacing the start.elf file but nothing happened
I have reflashed the image on my sd card and it works like that only before update there is no problem but after update, it is not booting

Try next time

sudo apt update && sudo apt dist-upgrade -y

an error came while i was updating using:
sudo apt update && sudo apt dist-upgrade -y
which stated the unable to fetch repository