Hello,
You may use SJC Disable Fuse for this purpose, please find more information about this fuse in the i.MX 8M reference manual chapter 4.13.5.4 SJC Disable Fuse, you may also find more information about this fuse in our Security Reference Manual.
As for the blow fuses procedure you may do this in uboot by using the fuse command:
=> fuse
fuse - Fuse sub-system
Usage:
fuse read <bank> <word> [<cnt>] - read 1 or 'cnt' fuse words,
starting at 'word'
fuse sense <bank> <word> [<cnt>] - sense 1 or 'cnt' fuse words,
starting at 'word'
fuse prog [-y] <bank> <word> <hexval> [<hexval>...] - program 1 or
several fuse words, starting at 'word' (PERMANENT)
fuse override <bank> <word> <hexval> [<hexval>...] - override 1 or several fuse words, starting at 'word'
Also, it may be useful to take a look to this thread for more option for blow fuses:
https://community.nxp.com/thread/480188?commentID=1161432&et=watches.email.thread#comment
Hope this helps,
Best regards,
Aldo.
