Note coreboot firmware update to MrChromebox-2606.1 and post-flash boot hiccup

CLAUDE.md

@@ -12,7 +12,7 @@
 
 This is a real **HP Chromebook 13 G1** ("chell" board), converted from ChromeOS to a normal Linux boot via custom coreboot firmware (MrChromebox project) and now running KDE neon as its OS.
 
-- BIOS/firmware: `coreboot`, version `MrChromebox-2512.2` (release date 01/25/2026) — confirms MrChromebox custom firmware, not stock ChromeOS firmware.
+- BIOS/firmware: `coreboot`, version `MrChromebox-2606.1` (release date 07/14/2026) — confirms MrChromebox custom firmware, not stock ChromeOS firmware. (Was `MrChromebox-2512.2` / 01/25/2026 as of initial provisioning 2026-09-03; updated via MrChromebox firmware utility same day — see note below.)
 - System: Manufacturer `Google`, Product Name `Chell`, Family `Google_Glados`, Serial `5CD732BLC9` — `Chell`/`Glados` is the Google Chrome OS board/reference codename for the HP Chromebook 13 G1.
 - Baseboard: Manufacturer `Google`, Product Name `Chell`, Serial `PFYTU018J90043`.
 - Implication: fanless Core m CPU, no way to add a fan — keep sustained-load expectations modest; eMMC (`mmcblk0`, ~29GB) is the original ChromeOS storage, while `/` lives on `sda` (117GB), suggesting an internal drive swap/upgrade was done as part of the conversion.
@@ -69,3 +69,20 @@ power-on cycles. The GRUB default entry (index 0, `GRUB_DEFAULT=0`) auto-
 selects the newest installed kernel, so `7.0.0-30-generic` is what boots
 by default now; `6.17.0-42-generic` remains available via the GRUB
 "Advanced options" submenu as a known-good fallback if ever needed.
+
+Setup script for a fresh install: `setup-i915-kernel7-fix.sh` (in this
+repo) installs the `Xsetup` fix and sets `GRUB_TIMEOUT=5` /
+`GRUB_TIMEOUT_STYLE=menu` so the boot menu is visible for 5s. Idempotent,
+safe to re-run.
+
+**2026-09-03, post firmware update**: updated coreboot from
+`MrChromebox-2512.2` to `MrChromebox-2606.1` via the MrChromebox firmware
+utility, then rebooted. First boot after the flash appeared to hang after
+the Plymouth splash (same visual symptom: backlight on, no image) and
+required a forced power-off. The *next* boot after that came up clean at
+SDDM with the `Xsetup` fix applying normally (empty `/tmp/xsetup-
+modeset.log`, one `FIFO underrun` as expected, pipe un-stuck as usual) —
+so this looks like a one-off "settle in" hiccup from the fresh firmware
+flash itself, not a recurrence of the underlying i915 bug or a new
+problem. If it happens again right after a firmware update, try a forced
+power-off + power-on before assuming anything is actually broken.