Can't connect to betaflight when battery is connected to quad

PsyBorg

Wake up! Time to fly!
OK... Several things can be stopping it from arming. First and most important REMOVE PROPS before doing ANY of this.

Lets start simple. Connect to usb and open Betaflight. Set the quad on a flat surface that is approximately level. Then recalibrate the gyros. the funny little picture of the quad should slide into a flat and level condition on the screen. Next pick up the quad and tilt it in all directions making sure it shows the correct orientation for the FC.

When all that is good go to the configuration page and set the arming angle to 180 degrees. That will eliminate any flags set for arming angle as well as allow you to arm if you get stuck in a tree at a bad angle or use turtle mode later for flipping over after a crash.

Next click the little button at the top just under the dataflash used bar that says enable expert mode. This will open up a bunch of other tabs on the left side with the one failsafe being where we check next. This page should be defaulted to where the craft disarms and falls from the sky on a failsafe condition. the stock time frames are usually ok to go with.

Now if you want to know more about stetting up a quad from start to finish I did a build log with EVERYTHING I do for a fresh build as well as the same setup for all existing builds I have once I got it all figured out you can check this thread which btw uses the mambf405 stack too. It has screen shots of all the tabs and setting I use as well as explanations in the order I set them up on a fresh build.

https://forum.flitetest.com/index.p...-the-oberon-ob-1-3-inch-quad-evolution.65728/