11-04-2021, 08:01 AM
There is no bootloader unlock. The boot order is baked into the processor and can't be altered by software or firmware changes, so unless there's a hardware problem you should always be able to boot from a correctly written uSD card.
Usually the problem is a mistake in writing the image to the card, such as:
* not extracting a compressed image that the writing tool doesn't handle automatically
* writing the image to the wrong place, often to a partition on the card (sda1, mmcblk0p1 etc.) instead of the whole device (sda, mmcblk0 etc.)
* corrupt image file download - forgot to check the checksum
If you can't find anything wrong then post the details of precisely what you did (which instructions you were following, which image file you used etc.) in case someone can spot something you've missed.
Sometimes it's a hardware problem:
* Broken uSD card (should be detected by verifying the image write, unless it's a rare intermittent failure)
* uSD card in SIM slot - don't laugh, it does happen!
* broken card detect switch in the uSD socket - rare but it can happen. There are workarounds but it takes a bit of effort. We can look into this if all else has failed.
Usually the problem is a mistake in writing the image to the card, such as:
* not extracting a compressed image that the writing tool doesn't handle automatically
* writing the image to the wrong place, often to a partition on the card (sda1, mmcblk0p1 etc.) instead of the whole device (sda, mmcblk0 etc.)
* corrupt image file download - forgot to check the checksum
If you can't find anything wrong then post the details of precisely what you did (which instructions you were following, which image file you used etc.) in case someone can spot something you've missed.
Sometimes it's a hardware problem:
* Broken uSD card (should be detected by verifying the image write, unless it's a rare intermittent failure)
* uSD card in SIM slot - don't laugh, it does happen!
* broken card detect switch in the uSD socket - rare but it can happen. There are workarounds but it takes a bit of effort. We can look into this if all else has failed.