Check your hardware connection on TELEM2 (1) to USB bridge (2): Tx1-Rx2, Rx1-Tx2, GND1-GND2.
Then use terminal program (e.g.
python-serial) to verify that pix sending something (data is unreadable binary stream).
Then check connection URL and diagnostics.
But by your diagnostics i may say that seems pix sending in other protocol than mavlink. Or baud rate mismatches.
Also you may use
socat for debugging.