Guide: BIOS-Downgrade from 5FCN95WW to 5FCN35WW

Question

hi! I've just upgraded to Windows 10. would it be safe to downgrade to 5FCN35WW? I've got the file from the time when I was using Windows 7.

Answer 1

 I have successfully downgrade my system (Ideapad Z580) to 5FCN35WW as it was written above. But I lost my serial number and UUID on my laptop. That was real trouble for me!Now I know how to prevent it.To prevent this trouble DO NOT USE switch /force when you type command on the console! So command will be the following: >winflash.exe /sv /sn /ipf bios ec /file 5FCN35WW.WPH with this command your serial number and UUID will not be lost. If you have already lost SN and UUID, you can fix them to do the following: NOTE:  I am not responsible for any damage on your machine!! 1. Find correct information for SN and UUID (for example on the carton of your notebook);2. Edit 5FCN35WW.WPH using WinHex editor.     At offset 181280 HEX in the text area of editor replace 22000000000000000000000000000022 by your correct serial number. Add spaces after your SN to fill all 32 bytes. All 32 bytes must be filled.    At offset 1812B0 HEX in the HEX area of editor replace 31 32 33 34 35 36 37 38 39 30 61 62 63 64 65 66 by your correct UUID. All 16 bytes must be filled. 3. Save edited file to 5FCN35WW1.WPH;4. Download UEFI WInflash 1.4.83.0 flasher;5. Now you have to hack environment.dll of 1.4.83.0 flasher (size 514 728 bytes). Open file environment.dll  in HEX editor (I used WinHex);6. Replace
68 01 00 83 C4 0C 85 C0 74 15
by68 01 00 83 C4 0C 85 C0 EB 15; Save environment.dll. It will allow you to flash your modified WPH file with wrong checksum. 7. Rename environment.dll (size 545 120 bytes) in folder of 1.5.66.0 flasher (C:\Program Files (x86)\UEFI Winflash) to environment.dll.BAK, then place modified one in this folder;8. Check twice, that you have done everything correct!!! Every modified file MUST be the same size, as it was before modification!!!9.  Open the console. Navigate into the directory of UEFI Winflash: >cd "C:\Program Files (x86)\UEFI Winflash" And now execute the following command: >winflash.exe /sv /sn /force bkfp bkoa3 /ipf bios ec /file 5FCN35WW1.WPH 10. Enjoy... This procedure worked for me. Don't forget to replace modified environment.dll (~503 kB size) by it's original version (~533 kB size), which was renamed to environment.dll.BAK.