Update:
I powered up the ecu using normal pins and pin 121. Got bootmode with MPPS without issue after.
The file I was using before was based on an .bin output from Winols, started from this file
http://nefariousmotorsports.com/forum/index.php?topic=4171.15. I think its corrupt as it only flashes a 330kb file but shows 1mb (can someone verify?)
Re-flashed the original file the ecu came with, and re read a 1mb file off it.
Flashed an SL file to it, and re read a 1mb file off it after.
Currently waiting for a new blue cable to arrive.......