hehe too bad dude...i also received that message from BSNL to upgrade firmware of my modem...luckily I postponed that....now I will never do that.
But one thing's for sure that your modem is not fried if you have upgraded it using legitimate means...
Switch off everything...let them cool down and restart I am sure it will work out as BSNL will not do send such upgrades which could increase their headache!