Error message "firmware update fail, will retry"

[airgradienthq]

When exactly is the error message "firmware update fail, will retry" displayed?

1. When airgradient server cannot be reached?
2. When image corrupt during download?
3. .. ?

[pnt325]

It's show when OTA perform failed like:

• Server not response or response failed.
• Image corrupt.
• memory issue (can not malloc new memory).
• OTA processing failed: start, stop, write data. etc.