Glad it worked!
About the CRC error on the first attempt, my best guess is that you were already on FW3/K1.04 when you tried the patched kernel the first time. In that state, the firmware update process may behave differently or run a different...
Please, I posted about this here: https://gbatemp.net/threads/ezflash-air-having-memory-issues-minutes-after-upgrading-to-newer-firmware.683449/post-10904224
Confirmed fix: downgrading from Firmware 4/Kernel 1.05 back to Firmware 3 (tested & working)
Note: I used Claude AI to help to articulate this write-up more clearly than my English allows. All technical findings and the patch itself are real and...