Mine was not booting and not even able to flash A11 rom. Basically no rom was flashing. So had to flash firmware.Hey bro, I was able to install the latest release, but I followed a different method as I did not want to loose my data, so here is what I did.
1. Installed the latest PE recovery via TWRP.
2. Booted the phone, downloaded the latest release from the Settings->update section.
3. Removed all passwords, pins, finger print used to unlock the phone.
4. Initiated the update from the update section.
The phone then restarted and completed the update process.