Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)

Method 1
ps aux | grep -i apt
sudo kill -9 <process_id>

Method 2

sudo lsof /var/lib/dpkg/lock
sudo lsof /var/lib/apt/lists/lock
sudo lsof /var/cache/apt/archives/lock

sudo kill -9 <process_id>

sudo rm /var/lib/apt/lists/lock
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock

sudo dpkg --configure -a

sudo apt update

Try 'sudo apt-get update' or 'sudo apt-get upgrade'sudo must be used before and after &&
Example:

sudo apt-get update && sudo apt-get upgrade