LFRAME
From xboxdevwiki
A old manual from XBox-Scene still is available from https://www.archive.org/ which explains how to reconnect LFRAME# for Cheapmods. This we don't care about, but the rest is what we want: Manual
Result should look similar to this in the end: [1]
In the end, we can gain debug output from serial again: [2]
This was tested on a 1.3 board, but should be the same on 1.4 and 1.5 too as the MCPX is the same.