Here 4 white lights, unable to boot or find hwID

Hi

We have been facing issues with here4 gps.

Out of 50 here 4 units almost 30 have same issue.

All stuck in white light during startup

2 here4 gps are connected to cube orange via splitter and splitter is getting 5v supply.

Few flights went well. And then all of a sudden these here4 jsut stopped during rebbot and gave white lights.

The firmwares were latest and these all were performing well for 5-7 testing flights.

There are lots of topics regarding same issue but no real output.

Would really appreciate if someone can throw some light.