Well assuming you correctly installed/flashed the firmware then I don't see why would your miner be dead, maybe you are looking into the wrong URL? this happens when you switch between Bitmain stock and vnish, and here is an example.
The miner's status page on stock firmware is:
<IP address>/cgi-bin/minerStatus.cgi
on Vnish it's very different
<IP address>/#/minerstatus
So maybe on Braiins OS+ the cgi-bin/minerStatus.cgi doesn't direct you anywhere, just use a different browser and enter only the IP address of the miner 192.168.xx.xx.
if that doesn't work, flash the miner with bitmain stock firmware using a Sdcard.