Totally my own fault, had connected it all together so the power came in from the battery, through the link and then split into each speedo. Connected motors and receiver, had laptop on with cable info for the receiver and speedo and it was all together spot on. Triple checked it for correctness and continuity as was petrified of lipo. Plugged up and stuffed the link in...BANG and lots of smoke. I know it will be the wiring shorting somewhere. So had a rewire from fresh. Started again and it powered and ran and then randomly popped again. I'm degree trained technician so did the usual methodical problem solving, swapped out my old loom n receiver and tried methodically working thru changing components. Same gear works great on sabertooth but plug botbitz in it pops n smokes. I've kept them.to one side n gonna have a look at others at the champs. Was mystified to be honest, suspect some weird compatibility problem, both becs giving to much power, so on n so forth. In no way is it the controller n definitely me wiring to cock somehow.