Colibri iMX7 Dual 1GB V1.1Bの起動不良について

It could be a log message. Doesn’t need to be a HW issue.
Please compare that with a working Colibri iMX7 Dual 1GB V1.1B

I don’t think so. It is more likely related to 3.

Yes, it could be a HW issue, particularly with the eMMC: Linux is having issues loading the Root File System (like mentioned in ②). Another option is that the eMMC contents have been corrupted because some writing was done during power off.

I would reflash the SW and test if that solved the issue.