FPZ image not booting - two green blinks

[Flavor]

Your /boot/config.txt should look similar to https://github.com/TheFlav/Freeplay-Supp...config.txt

The top is "stock," but you can find our mods after the
# BEGIN FREEPLAY MODS
line.

For your testing, I think you could just
==change==
hdmi_force_hotplug=1 #these HDMI lines will try to set up 1024x768 (you can remove them if you have problems playing via HDMI)
HDMI_FORCE_MODE=1
hdmi_group=2
hdmi_mode=16
hdmi_drive=1 #Normal DVI mode (No sound) (2 for HDMI with sound)
==to==
hdmi_force_hotplug=1 #these HDMI lines will try to set up 1024x768 (you can remove them if you have problems playing via HDMI)
#HDMI_FORCE_MODE=1
#hdmi_group=2
#hdmi_mode=16
#hdmi_drive=1 #Normal DVI mode (No sound) (2 for HDMI with sound)
====

Note that you could try hdmi_force_hotplug on or off, but I think there's no reason to let it try composite video.