the firmware update finishes, the page just informs you what it is doing
do you know the procedure to reset it? usually is just a button in the bakc of the unit, also conect via ethernet cable to the port 1 ion the lan connectors of the router, see if you can enter to the router ip, or is 192.168.0.1 or 192.168.100.1
if the firmware dies, sometimes there is a recover procedure, i had to do that alot with a old dlink router i had which i killed alot with custom firmwares, what model and brand do you have?