I tried to flash my HP Compaq CQ35-240TX’s BIOS to F.15 but unfortunately failed. The computer turned to white screen. When I restarted (powered off then boot again), this is no response any more: the hard disk and caps lock’s LED keep blinding. I thought "Oh my God! I must send it to HP to repair it!".
But after searching on the Internet and find there is a "crisis recovery" mechanism to recovery the BIOS even the CMOS don’t work. I finally managed to recovery the BIOS with a help of USB flash disk. I will introduce the procedure to crisis recovery my HP Compaq laptop. You need to prepare a USB flash disk and another computer that is connected to the Internet (we need to download the BIOS image from HP).
The steps to recovery the BIOS are as follows.
1. Format the USB flash disk’s filesystem to FAT16 on another computer.
2. Get the BIOS image from HP’s website (I use F15 version).
Download the BIOS update file from HP’s website (an exe file). Execute the BIOS update file on another computer. It will decompress the files. Select a directory to store the files and you can close the program. In the directory selected, we can get WinFlash.exe. Unzip WinFlash.exe using a program like WinRAR. We can find two .FD files. For my computer and the BIOS version I use, the two files are 306DF15.FD and 306EF15.FD. There are two model for Compaq CQ35 computers, so there are two .FD files. You may try one by one to see which model your computer use. Actually this model can be found in "BIOS Setup" (we can’t start it as the CMOS is bad)
3. Copy the file 306DF15.FD to USB disk’s root directory and rename it to 306D.bin. (the file may be different depending on the model)
4. Remove the AC power and battery from the lapttop.
5. Plug in the USB flash disk to the laptop.
6. Hold two keys: WinKey + B.
7. Plug in the AC power.
8. Hold the Power Button for 5 seconds, then release.
9. Push the Power button as normal to power on the computer.
10. After the laptop starts short beeping, release WinKey+B.
11. The laptop will keep short beeping for about one minute, it will power off itself after recovering the BIOS. If the laptop keeps long beeping or beeping for more than 3 minutes, the recovery fails, possibly because of the wrong image file or the USB flash disk doesn’t work on the laptop. In this case, you may try another image file or another USB flash disk.
Normally power on the laptop after recovering the BIOS and you will see the Compaq logo appearing again.
Disclaimer: I just tested the method in the post with my laptop and am not sure whether it works with one specific model (although it seems work for some others according to the comments). The method in the post is just one example solution. If your data is critical, contact a professional, such as the customer service from HP, to repair it for you.
Vadim‘s experience with HP Pavilion dv6740er may help if you have a similar model:
HP Pavilion dv6740er
After bios update my notebook failed to start – black screen+blue lights.
the BIOS recovery: