From: Software Updates 8 May 2018 - #9 by patrickelectric
Hi David,
The link that I provided here does not download ardusub.exe, but yes ArduSub-v2.px4.
Can you restart your ROV to try again the update with ArduSub-v2.px4 ? If it continue to fail, you can try to update the pixhawk with QGC, but for this it’ll be necessary to remove the pixhawk from the ROV and connect it via the USB cable in your PC.