Just going by their basic datasheet, you should have something like:
GPS_GNSS_MODE,0
GPS_TYPE,5
SERIAL3_BAUD,115
It might be the TYPE setting for NMEA that matters most.
Done that already, I have already got their “basic datasheet” lol
Read carefully, I have mentioned it starts for the first time and does not as soon as it reboots
Measure the supply voltage to the GNSS unit, it should be 5.0 volts or slightly more, but not less. They dont mention the current requirement unfortunately.
Also try:
BRD_BOOT_DELAY,3000
which allows accesories (usually CAN) to boot up and be ready before the flight controller finishes booting.