If i were you, i would use the sdcard method and be done with it. Don't ask me about the newer units as i haven't touched one (yet).
I think there is no solution yet to boot with SDCARD in a S15 machine.
New hint:
this exploit will not work, wrong parameters in curl, will only work on already opened firmware.
There is no create_log_backup.cgi, just on very old ones create_conf_backup.cgi. So it's the wrong CGI file to inject the code!
Good luck, and note nothing is for free.
If nothing is for free these post makes no sense!
There is many things free in this life like air, sunlight, rain...
Ok, even if we need to pay it, someone have the contact of someone that can unlock machines remotly for a fair price?
If everybody could unlock and overclock machines the hashrate would grow up, without hashrate going up, bitcoin cant go up, all we want bitcoin going up, so teoretically the guys that have the solution could post the solution and they could earn in bitcoin valorization, the problem is that guys are very smart in somethings but not so smart in another.
If i had the solution i would post for everybody.