hey @Mr_p I think I know what might be causing this. On the .dev image, the OS development team enabled a feature in uboot that would allow serial to interrupt the boot process so they could debug stuff in uboot. What I think is happening is the hat serial is sending random characters that interrupt the boot. This has been fixed in balenaOS 2.44 (I am told) which is on our staging server. So 3 options to work around this for now.
- grab the 2.44 .dev image from https://dashboard.balena-staging.com/ and put a config.json from your app into that image and then flash it
- copy the u-boot binary from the .prod to the .dev image you have.
- use the .prod image ( I assume this option is not appealing as it doesn’t allow for easy development)