After hours of trial and error and lots of research, it’s clear to me that this is by far the best place to ask for help.
First off the goal of what I am trying to do is simply change the splash screen image on a Lenovo Thinkcentre M82
It seems from the M82 BIOS update readme, that doing so should be an allowable function, but I can’t get it to work.
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*****************************************************************************
* 3. Flash Program Options *
* *
* wflash2.exe [option1] [option2] ... [optionX] *
* *
* [OPTIONS] *
* /h Show help messages. *
* /rsmb Preserve all SMBIOS structures. *
* /clr Clear BIOS settings. *
* /ign Ingore BIOS version check. *
* /sn:nnnnnnn Update system serial number (up to 20 characters). *
* /csn:nnnnnnn Update chassis serial number (up to 20 characters). *
* /mtm:nnnnnnn Update machine type and model number (up to 25 *
* characters). *
* /tag:nnnnnnn Update system asset tag (up to 25 characters). *
* /uuid The flash utility will generate an Universally *
* Unique Identifier (UUID), replacing the one that *
* is currently in the system. *
[b]* /logo:<filename> Change logo. The max supported size of logo file *[/b]
* is displayed on the screen during the compressing. *
* /cpu Update Intel CPU microcode. *
* /pass:nnnnnnn Input current system password. *
* /quiet Operating without physical presence. *
* *
* The following example shows how to update system asset tag number *
* to "1234567" use command line: *
* wflash2.exe /tag:1234567 *
* *
* The following example shows how to update bios and update system *
* asset tag number by one command: *
* wflash2.exe bios.cap /tag:1234567 *
* *
* The following example shows how to change the power-on logo. *
* wflash2.exe /logo:myfav.bmp *
* *
* Note: A flash update image using these program options should be *
* tested carefully before widespread usage. *
* *
*****************************************************************************
I perform that logo function but what I get an error "Child process failed. Return code: 74", see screen capture. I am running cmd as administrator. I have also tried a number of different image formats; png, bmp, gif. It seems to accept the image fine, compresses within limits, but fails whatever the next step is. Another thing I tried was performing this on a 32 bit instance of Windows 7. Originally tried on Windows 10 64bit. The image is a 640x480 image.
I have no problem flashing the bios otherwise, but this option does not work for me and with no support from Lenovo I gave up on this.
****SO****
The bios image is a .CAP file
Using UEFITool I imported the .CAP image. In the .CAP I was able to located the lenovo images (they are not in the standard GUID blocks for "logo" or "EPA logo" or anything like that. I found 3 of them in the following addresses:
4D3D82AE-2C3A-4C14-99BD-D59644EF6BC0
6C9013D0-4059-4723-AF2A-05E63FFECF19
83762026-D2AC-4A48-999C-D392C851A6C6
If you dump the raw data stored here you will get the lenovo boot image in .raw format that will open as a .bmp.
I modified the .raw files with my own image and reinserted them into those locations. (I will note that the size of the images inserted end up being smaller size ~200kb instead of 300kb, despite not changing much and keeping the original resolution).
However, I then fall victim to error 18 which is failing secure flash verification. If I could override secure flash, I think this would work, but I can't seem to figure that out.
I've disabled any "secure boot" options in bios. I've tried "ignore" functions in the flash tool. Nothing seems to work. Sort of frustrating and I've bricked two boards now.
I also note that I can't seem to override secure flash at all. Even using lenovo older images, it gives me the same issue, can't downgrade.
So I tried the /GAM method as recommended by this forum for boards without flashback
Using AFUWINx64 I flash using the original .CAP, which is successful. Then i follow with my modified ".ROM" which I complied by dumping the bios ("/O" function in AFUWIN) and edited the .raw files in UEFITool. When I load that rom I get "rom file size does not match" and if fails. Any other number of things I try otherwise gives me Error 18 Secure Flash Fail.
I'm really frustrated by now trying to do a relatively mundane thing and have become desperate for some help. Any advice or guidance I can try?
Sorry, no I don’t have any personal donation setup, but I appreciate the gesture and am happy to see you happy and issue is solved 
I wrote out too much to erase, hopefully it will help someone in the future 
