Currently looking into the same thing..
Start off with the firmware that is used by the DVR. Once you have the .bin, open it up and you see some .cramfs.img files and a InstallDesc
Open logo-x.cramfs.img with 7Zip (or something better if you have more knowledge than me), and you'll have a 800x800 JPG that is the boot logo.
Open the InstallDesc in Notepad and add the line on the Upgrade Commands
{
"Command": "Burn",
"FileName": "logo-x.cramfs.img"
}
Now the firmware will be able to write the boot logo in the img to the DVR. The only problem is I haven't found a way to properly be able to modify the .img, as if the .img isn't made properly, the DVR won't take the firmware and restart into normal system.
