Hm that is an interesting symptom. Do you have the serial or JTAG pins on the module exposed? If so, you can update the firmware and check to see if it is a firmware or a hardware issue.
If you have serial exposed, you can open up a serial terminal and issue a particle update command, followed by a particle flash --usb tinker command, which should update both your system and user application firmware.
If you have JTAG exposed, you can update your module to the most recent system and Tinker version by following the commands on this page:
@kmtm, this occured maybe once or twice and I had to move on. I have mounted more than 3 dozen P1s by now. I had the serial pads exposed and was not able to communicate with the modules directly.
May I suggest you check the power input pads specifically for the radio module, namely VDDIO_3V3_WL pin.
I’d be glad to give you more suggestions if you want to give more detail about your PCB layout, namely:
Are you using a 4 layer or 2 layer board?
What type of caps are you using for supply decoupling? Placements?
How often have you encountering this issue? Is it a consistently happening? Have you had any success with the same PCB?
How are you assembling the P1s? Reflow? Temperature? Duration? (Excess heat might damage the modules)
Do you use via on the solder pads? Different amounts of solder deposited to the pads might cause the P1 to not level with the PCB, causing potential open connections.
It is notated in our Product Creator Guide, but we highly recommend that anyone using the P1 in an integrated design expose both JTAG and serial lines to assist with debugging and reprogramming.