Death By BIOS Update 15-CS2083CL

[Bubbarosa]

I updated the bios to Ver F.32 (latest) for this motherboard.  After update it went through CMOS reset restarted a couple of time and windows started.  YAY!  Well not so yay after all.  After shutting down and restarting again... black screen and a 5-4 error on the caps lock.  Something about bios taking too long.   Tried the escape on the reboot to get into the bios and it just stops everything at the black screen but no flash codes, sometimes.  Tried a cmos reset, holding the power button down for 30 seconds while unplugged... no good.  Opened it up and removed the battery and restarted.. same.. 54 code.   Unplugged and tried theCMOS reset again... it rebooted a couple times and started windows.   So.. shut it down and restarted.  FAILED black screen and 5-4 flash code.   Next tried the CMOS reset with the battery removed and hit the esc button repeatedly and low and behold I was into the bios.   set the day, the boot drive ect and saved... WOW.. THAT WORKED GOOD.  Rebooted several times and all was good..... until I unplugged it to reinstall the battery.  Now back to the flashing 54 code.  Had to remove the battery again, CMOS reset, hit ESC to get into the bios and reset everythng and it started windows.  This time I thought about it and reinstalled the battery while still plugged in.. grrr.. but .. didn't toast anything.  It now works fine... up until the power cord and battery is removed.  Seems there is someting wrong with this bios.  Was going to flash back to something else but the notes on this bios say  ONCE YOU UPGRADE TO THIS BIOS YOU CANNOT DOWNGRADE DUE TO SECURITY REASONS.  So now what?    BIOS I.D. is 84C0 F.32 by INSYDE. is what the computer says in in there 

[Max3Aj]

@Bubbarosa, Welcome to HP Support Community. 

Thank you for posting your query, I will be glad to help you. 

It sounds like you're dealing with a frustrating BIOS issue on your HP Pavilion 15t-cs200 CTO. The 5-4 error code indicates a problem with the BIOS taking too long to initialize. Here are a few steps you can try to resolve this:

Keep RTC (CMOS) Powered

This model heavily depends on battery or power to retain BIOS/RTC config:

• Keep the main battery installed.
• Do NOT let both battery and AC get disconnected — that triggers a full RTC clear, and boots start failing again.
• Plug in AC power before reconnecting the main battery, as you've discovered.

Reset Embedded Controller (EC)

Try a deeper EC reset:

1. Disconnect AC and battery.
2. Hold Win + V (or sometimes Win + B) + Power for 15 seconds.
3. This should trigger an EC recovery or BIOS recovery screen.
4. If screen stays black, wait 1–2 minutes, then reconnect power and try booting again.

Attempt BIOS Recovery via USB

You might be able to force BIOS recovery using a USB stick with the BIOS image:

How:

• Format a USB flash drive as FAT32.
• Download an earlier BIOS version for your system (e.g., F.30, F.28) from HP.
• Use a tool like 7-Zip to extract the .exe and look for a .bin or .fd file (typically 084C0.bin).
• Rename the file to HPBIOS.BIN or BIOS.BIN depending on model.
• Place it in the root directory of the USB.
• Insert into USB port.
• Hold Win + B and press Power for 3–5 seconds.

If these don't work, then we suggest you please visit the nearest HP authorized service center, the service team will check and assist you further. 
Kindly follow this link to locate the nearest HP service center: HP® Service Center Locator - United States | HP® Support
(Select the country from the dropdown menu and enter the city name or pincode) 
 

I hope this helps. 

Take care and have a good day. 

Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Select "Yes" on the bottom left to say “Thanks” for helping! 

Max3Aj

HP Support 

[Bubbarosa]

I flashed the bios via external flasher CH341, back to F.28.  It temporarily went back to booting normally, no 5-4 flash code, but the shift key problem ramained.  After several reboots, the 5-4 flash code came back.  So in order to reboot, I did a Win+B with no USB stick installed, and this time instead of saying it couldn't find the back up bios, as it was doing before, it started reloading the backup... which happened to be  the missing F.31 that is not on the website any longer.  Hmm.. Well HORAY HORAY!!!   I have not rebooted 20 times and the 5-4 flash code is gone.  But..both shift keys no longer work... again.  So.. I went to HP diagnostics and did a keyboard test. ... alas... both shift keys still inop on the first test screen... then I go to the next where you press them with another key and whoa.... they started working.  I'm wondering if the windows keyboard drivers are doing something here overriding the bios?  hmm.. don't know how that works.. so.. I go to notepad and type all the CAPS I want with the shift key.  Great!  but... I let it sit for a while running, and come back about 15 min later, and the shift keys no longer work.  again.. do the diagnostics and after playing with the keys several times.. they start working.  Keyboard has been changed to a new one because the original was doing similar stuff.. no change on the keyboard change.  Motherboard has been changed also.  The common point is the F.31 bios that was on both boards that does not exist at the HP website any longer.   My once nice laptop, albeit 4 years old... is AFU.  It's a pain in the butt using ALT+58 to type a colon in order to change drives and such, but doable.   C:\  ...    D:\ ...  I'm not sure where to go from here.  Another used motherboard seems like excessive for a firmware issue.   There has to be a way to fix this easily and simply.   How about a new BIOS update called F.33 that repairs the havok that F.31 caused me and I'm sure others.