EDIT: Didn't see your edit & Everything's fine now... So you can ignore me 
Anyway, which discs don't boot? Original/Backup PS1/PS2 DVD Video etc?
Do you see the 'Matrix' logo on initial power up of the machine, or does it boot straight to the 'Sony Computer Entertainment' intro video as per usual?
As for the F wire - if its for DVD-RW and the diagram states it's optional, then you don't necessarily have to install it if you don't want - but for the sake of one wire you may wish to consider it anyway...
P.S - Yes, A-I on v15 are the authentication points on the C/DVD Controller, but if you dont see the Matrix intro screen and cannot disable the chip or access the chip BIOS etc then the problem is deeper rooted than a simple wire switch.
Another important point to consider is the fact there are 2 sub-revisions of v15 - the GH-051-02 and the GH-051-51 - make sure you're using the correct diagram by checking the serial number on the board itself against the diagram you're using...