Cannot remove anti-tamper box above ECU

Apart from grinding the top off, how does one remove the box above the ECU on the back of the engine, despite the dial wheel inside it apparently being brass, it is somehow stuck solid and refuses point blank to move and even snapped a drill bit without bugging a millimeter. I've tried moving it up and down, having someone pull it as I've tried turning it but this was to no avail.



I've also tried a good old hammer and chunky screw driver which has bent it a little but not nearly enough to get inside it and turn the wheel by other means.