Once you successfully unbrick your device using v1.8.6, immediately disable automatic system updates in developer options. An OTA update could re-lock your bootloader or re-introduce the bug that bricked you in the first place.
It can revive "dead" or soft-bricked devices that cannot boot into the OS or Recovery. msmdownloadtool v1.8.6
Using MSMDownloadTool v1.8.6 requires some technical expertise and caution to avoid damaging your device. Here are some steps to follow: Once you successfully unbrick your device using v1