DJI Matrice M100 Conversion Log

Wanted to make a log for the process where we are reviving an 9 year old new in box DJI Matrice 100 drone. The goal of this project is to install a pixhawk 6 series flight controller onto the drone to enable manual and autonomous flight.

This thread will differ from the px4 doc on the M100 as i would like to discuss the hardware/battery/setup a little bit more in detail.

Currently, the reasons for reusing this frame are as follows:
-We already have the frame, some costs can be saved in terms of motors/props/motor controllers
-The frame can lift up to 1kg it seems which will be more than adequate for our payloads
-Would be a shame to toss a new in box system
-DJI motor controllers seem to follow a standard communication protocol based on the px4 doc on the m100. This should allow for
-Large upper platform should easily allow for the addition of a compute module
-Large payload capability should allow for 8000+mah battery setup

Projected challenges:
-Ensuring we can throw the garbage TB47D battery away and use a standard 6S system. The difficulty of this will depend on how the battery system is integrated. I suspect it should not be a big issue given that we are replacing the flight controller.
-Sizing a 6S battery to replace the TB47D. Estimating the current rating of the 47D will be the only technically challenging part.
-Ensuring long range comms function correctly.

Projected costs:
-6S battery
-New radio system (may use a spectrum DSM controller kicking around)
-Pixhawk 6 Series (leaning to the 6c, but the mini or x may be used)
-Adding in telemetry: Sik series system for a base station setup. Seems to be plug and play.

Resources:
PX4 Docs
https://docs.px4.io/v1.11/en/frames_multicopter/matrice100.html
Did not make this but hoping to update some diagrams as i go through the system.