94 ford f150 xlt. cranks but no start. plz help

I went to look at this truck and the guy used a
jumper box hooked to the battery to crank. It had
been sitting up a while. It drug at first which I
assumed was just a weak battery but it started and
ran great. It had a flat tire from sitting so I couldn't
drive it but it ran so well I decided to buy it. The guy
told me that he thinks the radio wire was draining
the battery and kept talking about thinking that it
needed a regulator so it kept blowing fuses. After
buying the truck and doing the title I went to get it
and suddenly it would not start even with the
booster box. He said it must be out of juice. So I
took the battery home and tried to charge it. My
charger kept saying bad battery. So I didn't use it
anymore. I took another charged battery and it
would not start the truck. It cranks but no start. My
brother came with me. He said it wasnt getting any
fire. So we blew up the tire and pulled it home.
Replaced the ignition module. Put a new distributor
in. Put a new coil in. And took the radio out to find
that it was hooked up wrong and blowing all these
fuses plus draining battery. We replaced all blown
fuses. Put in gas. Still no start. My brother who
was a mechanic for many years says he doesnt
know why it wouldn't start because all required
things for ignition are now replaced. It just cranks
but not start until it kills the battery. What is weird
is that it did start when I went to look at it just days
before.

I doNt know much about the mechanics of trucks.
What else could the problem be? Please help if you
can. Its very frustrating. I would be eternally
grateful.