The diagnostic wrapper phase (magenta fill, 3-blink train, 5 s hold)
is removed; the shim keeps only the load-bearing display revival
(OVL_EN, OVL0_2L_EN, backlight GPIOs) and the patched branch to
U-Boot. U-BOOT.md documents the boot chain, payload layout constants,
build/flash/verify commands, recovery and the U-Boot tree state.
U-Boot was rebuilt with the user's hand-tuned .config (16x32 font,
CONFIG_CHROMEOS) without re-running the defconfig.
vhaudiquet