Pixhawk2.4.8 for Rover
1.Upload the V3 firmware
Select fmuv3, NOT OTHER.
also you can download the V4.0 version here https://firmware.ardupilot.org/Rover/stable-4.0.0/fmuv3/ardurover.apj
2.How to connect to Mission planner?
if you use Mission planner greater than 70,you may meet this problem,
Rover V4.0 has a bug. Mission planner greater than 70 cannot be used, because Mission planner after 70 use mavftp, V4.0 has a bug, and the connection will disconnect and restart the flight control. Copeter and fixed wing have fixed this bug. We can see from the version release.
We can see that the mavftp restart bug was fixed from the 4.02 version branch code, but the rover firmware stays at V4.0, so this problem exists.
How ot connect to Mission planner? has two way.
If you use V4.0 Rover firmware, please download the 70 version of Mission planner, do not use greater than 1.3.70 Mission planner, which can be downloaded here: https://firmware.ardupilot.org/Tools/MissionPlanner/MissionPlanner-1.3.70.msi
You can use Rover firmware greater than V4.0, but the Mission planner has not been released, so you can only download the latest firmware from the official website: