Try with OsxAptioFix2Drv-64.efi. Also, make sure you try all USB ports, both with USB2 and USB3 flash drives.
Thanks! I replaced the Aptio driver with AptioFix2...
All 3 USB slots have a blue logo - 2 ports on left, 1 on right. I recall reading the laptop has 1xUSB3 and 2xUSB2. Am presuming the sole USB slot on the right is USB3 and the ones on the left are USB2. The stick is USB2 anyway.
Using 191b0000 for the Intel video (manually overriding what's in Chameleon), and using USB port on the left, I finally made progress. However, instead of the OS X install screen I get garbled text and a circle with slash. This required holding the power button 4 seconds for the machine to turn off.
Turning off the laptop and moving the stick to the USB port on the right side, then using 191b000 again, I got stuck at the 2-line screen with the Aptio fix and line below it. Using 191b0001 (a fake id) had no effect.
Going back to the other USB port (left side), trying 191b0000 had no effect - 2 lines in and it would stop.
I also noted that, on the first bootup where I saw progress, the Clover screen was blue and had a basic text motif with basic graphical icons. Subsequent boots had a nice black screen and glossy detailed icons.
I doublechecked all BIOS settings (1.1.5, still can't believe it) - all were identical to what's in post #1. I even changed other settings to the most basic settings, etc. Nothing had any affect. Still bizarre how rebooting after that first time, with the blue Clover screen that got me anywhere, would change and look different on every subsequent boot attempt.
Another idea tried: In BIOS, checking USB Debug mode and enabling it, the subsequent reboot had the basic blue Clover screen (191b0000 as well) - but it halted 2 lines in. I kept the stick in the same slot (right side), powered off, then rebooted and went back into the BIOS settings.
Going back into misc devices/USB Debug->Disable then rebooting, trying 191b1234 -- this worked, until the slash with circle returned.
I then rebooted (ctrl-alt-del) and used a new address, 191b2345, and checked the boxes for InjectEDID and LoadVideoBIOS. This worked past the "typical 2-lines starting with OptioFix" but still got the circle slash. I tried this on both right side and left side USB ports. Still got the circle slash each time and soft-booted when trying other addresses, otherwise powering off to switch USB ports.
On some reboots, having to change graphic IDs to 191bnnnn had to be done to get across the initial 2-line hangup point, but all for nought as I'd still get the circle slash with garbled text underneath...
Using a USB2 port hub in any of the USB3 ports had no effect either.
One thing I can mention - I left the computer at the garbled screen with circle slash. At the bottom, it reads "xxx waiting xxxxxxxxx" (x= unintelligible garble though the last word could read "event" and the word before "waiting" looks like it might have a "m" and something next to it) and every so often a line return/blank line appears after the screen flashes. When trying a boot without -v, all one sees is the circle slash and no text. GraphicsEnabler=No did not help. It's as if it's trying to load the graphics but failing...
In all cases, "FakeID" for the graphics injection I left at the default 0x00000000...
