OP I have the same issue, we can't downgrade using any of the above mentioned tools
Some how we are the few who have the latest Bootloader, I think it's 5.09 or something, excuse me for not typing it in correctly, I'm new to this,
However afte many attempts and google searches, I feel that we are sitting ducks until the wizards figure out the new tool/break for us tounlock our latest Bootloader
I'm only assuming u have the new boatloader since u can't downgrade
Any other options any other members have please let me know
All I know I don't want to go with the 6.15 version