thats’s the exact Logo.bin I’ve used and deeply modified!
As for the checksum, I’m not sure how to do it, and Giomen post is not 100% clear to me.

I’ve understand I can manually calculate the checksum (don’t really know how, which method, CRD, MD5 ??), for the entire region 16 ( including slpash lader? or only the BMP part?,
and put that Checksum value as the last byte in Region 16 (That I can do, as I know where the BMP “payload” ends in my custom Logo.bin

Maybe I’ll give it a try later one day when I figure out how to manually calculate checksums for any amout of data.