Won't start & burning out Starter relay, V-6.

Truck just up and would not start. Not enough juice
in truck to even unlock doors. I jumped it and took
an hour on the relay charge to even get the dash
lights to come on. Put new battery. All lights, locks
& etc fine. Still will not even turn over. No clicking or
anything. I looked at starter relay and decided to
switch it with another relay because they are exact
same. Made the switch and the truck started right
up but died real quick. Like the old vehicles did
when they were carbureted and cold. Went to start
again and it is just nothing again. Lights and all are
ok. It is frying starter relays. WHY?  Truck has been
sitting basically since my husband passed away in
Aug 2016, and rarely started.  Also upon it being
driven about 10-12 blocks in late Aug, the check
engine light had popped on but I haven't had a
chance to check to see what code it was throwing.
Hoping that with it sitting sonling with what seems
to be a totally dead dead battery, that the code is
still there now to check. Now for a bit of a twist,
there has been a few people noticing it sitting and
have been bugging me to sell it & rather insistant
that I sell it as an "as is" vehicle. IT IS NOT an as is
truck. It is a sharp little truck, rather harder to find
little 4 door, 4X4 truck.  One guy has been literally
harassing me to sell it to him dirt cheep. I wonder if
he hasn't sabatoged the truck to give me a reason
to sell it cheep?  Maybe maybe not. A thought
though but I can not think of what he could have
done to make it do this. Anybody have a truly good
suggestion as to what may be wrong or where I go
next?  I am a cancer survivor and on a very limited
income, so just taking it to a good shop to figure it
out is not going to happen. Electrical problems get
to expensive to just diagnosis. Any Erich's good
suggestions, I need fast!  Even email me with the
subject of "relay" would be great too. Thanks!   
cindystewart440@yahoo.com