you will need to get a willem programmer with a tsop socket and also the old firmware file to match your model number eg 100,120,200
then u need to lift the tsop from the modem and reflash the old firmware back and refit the tsop
its not worthwhile buying the stuff to do this unless you have a few friends with the same problem m8 who r willing to share the cost
advice is get a surfboard while it lasts