Hi
"balenaEtcher says that it is not a valid image."
Is as https://imgur.com/vzanC6G ??
Missing Partition Table Issue --> https://forums.balena.io/t/missing-partition-table-issue/175129
[Check]
(1) My Mac load normal. My Etcher version is 1.5.116
(2) My Tinker_Board-Debian-Stretch-v2.2.2-20210326.img size 3.38 GB (3,631,173,632 bytes)
(3) md5sum Tinker_Board-Debian-Stretch-v2.2.2-20210326.img
07385e98a4c3689d396409fb48508c65 Tinker_Board-Debian-Stretch-v2.2.2-20210326.img
How about you??