testing no leads packages for pin to PCB pad connectivity
Curve tracer maybe?    That's a homemade one.  In the factory you usually x-ray, then put the board on a tester that does something similar. If you have a known good board you can probe it and get the resistance to gnd, to other pins.  Then as @Manu3l0us suggested your diode tester to GND or power.  Then compare between your board.

If you don't have any tools... Turn it on and start probing to see if it works.