I have an ASUS Zenbook S 14 UX5406SA that stopped booting normally after I installed BIOS version 310 on 2026/08/12 through MyASUS and Windows Update. Pressing the power button results in a black screen with no BIOS or Windows startup, and the keyboard backlight briefly turns on before fading. Holding the power button for about 40 seconds starts a "Working on memory training" process, but the laptop shuts down once that finishes. F2 does not open the BIOS, and the behavior changes when the charger is connected. I also tried preparing a FAT32 USB drive with the official UX5406SA BIOS 310 file, but I cannot get the firmware recovery screen to appear. Has anyone experienced this after BIOS 310, or found a reliable recovery method?
2 Answers
I’m seeing the same symptoms on my UX5406SA. So far the firmware recovery shortcuts and USB recovery have not worked, and I have not found a fix yet.
Use the original ASUS charger and try the memory-training process once without interrupting it. ASUS notes that memory training can take around 5–10 minutes, so leave it alone for at least 10 minutes. If it still powers off, prepare a FAT32 USB drive with the UX5406SA BIOS file renamed to UX5406SA.bin. Insert the drive, power on, and try Ctrl+R repeatedly. If that does nothing, try Ctrl+Home and then Ctrl+Fn+Left Arrow. If none of those combinations brings up the firmware recovery screen, it is probably best to contact ASUS and explain that the laptop became unbootable immediately after BIOS 310.
The memory-training stage can take surprisingly long, especially if certain performance or AI overclocking features were enabled. I would give it the full amount of time before forcing it off again.
Same situation here—the recovery screen never appears, even with the correctly named BIOS file on a FAT32 drive. This may require ASUS service if the extended memory-training attempt fails.