2002 f-250 will not start

i turn the ignition on and hear nothing but relays popping and no crank. i turned the ignition and held it on for about a minute and heard the relays popping and saw some idiot lights flicker and it actually cranked and started for a brief second then died. the battery has been tested , i've replaced starter relay and ignition fuses-nothing. this is a 2002 ford f-250

first thing is check your starter relay. it's in the central junction box behind left lower side of the dash. switch it with another relay that is the same and see if the starter runs then.