1990 Mazda B2200 No power yet battery is fine

Engine Mechanical problem
1990 Mazda b2200 4 cyl Two Wheel Drive Automatic

Truck will not start. Tried jumping it, but when turning the key to start, all power was lost, headlights went out, dome light went out, everything. Started again last night, worked fine for 24 hours, now mimicing the same problem. Pulled the key out of the ignition, waited a few minutes, tried again. The lights came back on, but the truck did not even make an effort to crank. Tried for a third time while trying to jump it, and again it lost all power. No odd noises, wiring looks good from what is visible. Distributor cap is fairly new.