The battery is strong and full charge we just had a charger on it and we tested all of our connections we could find and they are all good she fired once on her own i shut it off now she wont start againIf you can boost it then you battery is weak. Did you charge up the new battery with a charger. New batteries rarely come fully charged.
I just got Thru yesterday working on 1989 Dodge D250 5.9 cumming .The Alternator went out so we bought a new one it looked right installed it & within 5 miles it quit charging .So took it back I asked what Amp was it it was a 80 Amp . The book calls for 120 Amp got a 120 Amp & went ahead and replaced external voltage regulator .Since they have had issues with the computer telling the Alternator to over charge the battery .anyway I had a bad external volt regulator & replaced it with 120 volt Alternator from Napa .worked fixed it .Hope this help u out .It’s the ground. If it starts with a jump, it’s the ground. Make two or three ground from 2 or 4 gauge wire. Battery to engine from that engine ground to frame. And from battery to frame. Your starter is grounded and bolted to engine but there’s just not enough ground.