Brick means it is no longer a router and unless you know how to de-brick it, it will never be a router again.
google for dd-wrt (openwrt) and visit the broadcom forums, all questions answered there, the thread on captive portal hotspots (chillidog) is about 50 pages, walks you through setting up a linux server with all the toppings.
DO NOT use your routers "upgrade firmware" option, instead use tftp to flash the router.
ALSO be careful using the backup / restore feature as it may brick the router.
This is all covered in the forum.