Think I've figured out why.
The ECU I bought was supposed to be a L6 but looks like a L1 so that's why my MSD chip won't work in it.
The seller says it's a Bayjoo chip - is there any way of finding out what the spec might be from the sticker on top?
The top of the chip says "3BL1R26.803" which (as a guess) I'm thinking:

3 bar sensor
L1 ECU
R26 - no idea
803 - greens

Might be totally wrong though