[iceweasel]

Have you connected the +12 MOST? It is a small connector 4 poles, a wire +12 is enough

In the MOST connector (on the amp) there are 4 small connectors (number 1 to 4) - I jumpered pin1 & 2 together. When jumpered there is 12v on pin1, and 12v on pin2. When not jumpered, there is only 12v on pin2 and 0.0v on pin1.
Are you saying I should run a 12v wire to pin1 or pin2 separately and not jumper the pins?

I haven't done many NBT EVO Retrofits on E series that fitted F series AMP. But a general notice, have you tried to "Store MOST configuration" either in ISTA or actual headunit inside Tool32.

I have very limited coding experience, as such, I’ve never done ECU coding with those tools, so I don’t know how to answer that question.

Another tip, just blindly firing from the hip here
Ff everything is connected and kl15 ON - can you remove MOST connector from amplifier and check that INCOMING and OUTGOING light output is active.

This one I can answer. I did remove the MOST connector, and the incoming light was active, and the outgoing light on the AMP was also active.

Last one:

What is your HU_NBT2 cafd > 300D KOMBI > EINHEITEN_MASTER set to?

It is set to kombi_l6 [01]

I hope I answered your questions clearly