I downloaded the new iso and verified the checksum.

Generated a new serial log. Same problem.

https://www.dropbox.com/s/ercnfnmjit2mos7/teraterm6.log?dl=0

BTW the bootloader gives some error messages:
Failed to load cache block 0 from device 2
Failed to scan partitiuons on device 2

What do these messages mean?