The Mavics  remote has a feature called charging mode that will charge your phones battery if it goes below 40%. If I put the remote to charge while in use and while charging the phone will it damage/FRY the remote or its charging boards if used that way?

Worked for me and did not damage anything.

I try it, it lost signal. the Mavic started to come back when I was able to link my control back to my Mavic and continue my flying

Hi, Thanks for the inquiry. If you're referring to the Mavic 2 Pro, this feature is available on the iOS device, however, using this may cause the RC to drain faster while using since the mobile device is charging. Regarding the concern about the charging the mobile device. It should not affect since our engineers tested it and provide an option of doing this. Thank you for the support.