mtkclient does not seem to correctly interpret the usb output of the device past some part of the early boot process. Really, any of those messages formatted by mtkclient are unfaithful to the intended meaning. So yes maybe it is "just a checksum step" or maybe something else entirely. Last year I collected some UART logs on the device during bootup in a zip here:

https://github.com/bkerler/mtkclient/issues/1289