Is the 5120 even worth the hassle?

After shooting my mouth off about how easy it is to mod a surfboard modem, a friend of mine asked me to mod his SB so i open the box and its a 5120. I then proceed blindly into flashing it with my USBJTAGNT assuming it was similar to a 5101. I was wrong. I bricked the modem and and reading about the watchdog. The chip is detectable but I just dont have the patience to give it another go after reading how shitty these modems are.

Is there a better way to go about this, or should I just throw this thing away and concentrate on the 5101N I have laying around.