1.
Remember differences between prototype/sample and retail devices...
So check if your device is retail... remove battery look on label...
"Not for sale" or something similar could be on label...
2.
Bootloader... maybe for Tizen Special Bootloader...
I have read short something about this somewhere forgotten...
Because Tizen is cra...
So the Question is, if you can generally update your Tizen devices with Tizen for instance...
Or you have never tried... Maybe other problem...
3.
Maybe better or safer choice is to use your Tizen devices with Tizen...
There are different Versions available... instead risk to brick your Tizen device, by stupid mistake.
4.
You could sell your Tizen device.
Best Regards