I am hacking a chinese smartwatch. I extracted a animated GIF from its firmware and edited it to test my tools. The new filesize was less than the old one, so I added zero's with
trunk command on Linux. However, after writing back the ROM, it refuses to boot without showing me anything. A friend of mine suggested me that there might be a simple checksum at end of file. However, I am unable to determine what kind of checksum it is in order to add it to my edited file. I added two sample files in this google drive folder (0 and 1 .gif). The original userspace firmware is FILE_01_mtk. If I look at the first file, there are only a few bytes after the '3B' marker (probably end of GIF). However, the second GIF is completely different, with the '3B' alot before.
Can someone help me figure out what checksum or hash is used?
Thanks, Alexandre Croteau