According to Newton's Second Law, the conditions for equilibrium are:

1. The vector sum of all the external forces on the body MUST be zero.

2. The vector sum of all the external torques that act on the body measured about any point MUST be zero.

(That is because based on Newton's Second Law, if total momentum is a constant, the total net force MUST be zero, and based on Newton's Second Law for rotation, if total angular momentum is a constant, the total net torque MUST be zero!