I received my mini 3 last week - I've been getting sporadic E-03 (power failure) errors from the start, if it's on any setting other than eco.

It says it has a hashrate (30TH/s on eco) but it's not actually submitting any work... the logs are full of "ERROR job_id compare error"...

Canaan support has been responsive, but not entirely helpful.  "Send us a video of the problem...", "change your pool settings", "do a reset again", "are you sure it's plugged in properly?"... ffs.

Unit seems defective - but they don't seem too interested in actually taking it back/repairing/whatever.