We just had our first run using the BL600 or BL620 module and the prototypes are not working?

The BL6x0 has very fine pitched pads and if too much or not enough solder paste is applied, this can cause an issue. Stencil thickness and number of passes used to apply the solder paste using the stencil should be controlled. In our own manufacturing process we have found that a 5 mil stencil with a single pass of solder paste is the best process to use.