Please help me! Starter replaced 2x.

This is going to be a fairly long thread detail.  Forgive me for my terms as I
will do my best to explain without having much vehicle terminology.  I know a
little about cars, but I am no expert.  

My 2008 Acadia started having issues starting.  My driveway had an incline
and I would notice when putting the car in reverse I could hear the car exiting
park to reverse, or hear when putting the park in park from the forward
driving gear. This was the first thing I can recall and I do not know if it even
plays a role in the overall issue.
      I had some issues starting my car at times and I would have to push the
gear up to ensure it was in the parked position for it to start.  This was not an
every time I cranked it occurrence.
     One night, I was at my storage unit. I was organizing things so I was there
for about 30-45 minutes.  I had my car off, but my door open, and my phone
was connected to the after market bluetooth adapter I have in my car as I
was listening a podcast.  I finished and went to crank my car, but it would not
start.  The lights were dim until they eventually faded off completely.  I called
someone to jump me off and it was successful.  He suggested I have my
battery checked because it shouldn't have drained that quickly.  I did so and
it tested good.  My car would not start a couple of other times before one day
when it happened a guy who seemed to know a thing or two about cars
helped and told me it was my starter.  He banged it and it started.  I told the
guy who told me to have the battery tested and he told me he would help me
change the starter.
     I purchased a new starter from PepBoys only to discover they sold me the
wrong starter to my car AFTER we had taken the one in my car out.  It was
late so we could not take it back then and had to put the starter back in my
car in order for me to get around the next day.  I took the starter back to
PepBoys but they did not have the one for my car because they are in the
process of closing their retail side.  My friend helping me told me I could
purchase a used one from a local place so I did that instead of waiting on
one to come in.  
      He installed the used one and my car started fine for about 24 hours.  It
was a little hesitant to me, but I thought maybe I was just paranoid until the
day it didn't start at all.  I could get it to start by either pushing the gear all the
forward, or putting it in the neutral position.  This worked for the first few
times it did not start, which was not every time I cranked the car at this point.  
Then it started to not start even when I switched the gears, until it didn't start
at all on 02/22/2020. The engine would not turn over yet the starter sounded
like it was running and did not stop nor could I take my keys out of the car.
This was about 3-4 days after the used starter was put in.  
     My friend came to try and jump my car off, but it was unsuccessful.  He
said my jumper cables were bad, but I argued with him because I just
purchased those after he had to jump me off at my storage.  He showed me
the positive jumper cable and how wires were exposed and I said that
cannot be I looked them over before buying and I know they were properly
connected.  He said no, they're not and promised me he would be back early
the next morning to get the car going (this was late around 11pm at night).  
Well I ended up calling my co-worker before he could get to my house and I
hooked her jumper cables up and attempted to jump my car. The sound of
the starter came on, and my lights were on although dim, but the car would
not start.  I noticed smoke coming from the cables and discovered my car
was burning the cables and I immediately had her turn her car off and I took
the cables off.  My cables were good until my car burned them, as were my
co-workers cables.  
     My guy friend arrived shortly after and told me that it was likely the starter
harness because we did not replace that.  I was skeptical.  He said he would
go get the replacement and replace it.  He did that and advised he put my
battery on to charge and I could put it in my car later if the green light was on
the charger.  A few hours later I saw the green light and put the battery in my
car.  As soon as I connected it to the terminals the starter began to go again
and I tried to turn my keys in the off position to take them out, but it was still
stuck.  The starter only ran shortly until the little battery that was in there
drained away.  My friend that was helping me took the old starter that we
initially replaced and had it tested.  He said he ran it 3 times and it ran good
so he reverted back to it was a battery issue.  
     My sister took it upon herself to call a mechanic she knew to come and
tow my car and commissioned him to repair it.  She would not share many
details as she and my mother were not keen to the idea of a friend making
repairs to my vehicle.  They wanted this shop, which is owned by my sisters
client's husband, to make the repairs.  Three days in and I finally got the
address out of her because I had to get my keys to my house, and work off
of the key chain.  I went that evening to get the keys and I took a look under
my hood.  I observed the starter as removed and the manifold components,
along with the catalytic converter out of place which only indicates he has
removed the starter.  
  I called the shop the next day to talk to the mechanic to understand what
went sour and what his plan for repair was.  He said I had a shade tree
person working on the car and they clearly do not do it for a living, which he
does not, and there were rounded off bolts.  He said he was having the
starter rebuilt as I burnt it out when it was running and he was surprised my
car did not catch fire. He advised he could not diagnose until the starter was
rebuilt and was able to run diagnostics.  I told him I had a starter in the
backseat that tested good, which he would of seen when he disconnected
the battery to remove the starter because it was on the back floor board by
the battery.  He said it was too late because he was having the other rebuilt.
He advised the starter would be ready the next morning, which would of
been a Thursday and he was behind, but planned on working Saturday to
catch up.  
     I called on Monday afternoon and he recited the same story to me as I
asked when it would be repaired or if he could give me the diagnosis of the
problem.  I asked him how much is invested in it now for me to come and
pay him and I would have my car towed some place else because each day I
am paying for a rental.  He said I was asking questions that he was not
prepared to answer, for me to hold and he would let me know, although he
strongly suggested he finish the work as I have had "shady people" working
on it.  I said okay, well, I was not prepared for my car to be in the mechanics
for over a week and having to extend the rental for an unknown amount of
time.  He came back on the line and told me $519.  I asked for a break down
of the cost.  He said $234.55 for the rubuild of my starter, $200 in labor, and
$85 for the tow.  I stated that a brand new factory OEM starter is $140 and to
rebuild an existing one is $100 anywhere in town, or you can buy a rebuilt
one for $135 from any automotive store.  He did not say anything.  I went on
to ask how much his hourly rate was, he said $100.  I said, so it took you two
hours to remove the starter?  He said yes, it was connected to the exhaust
manifold and catalytic converter.  I said I know, I removed the first one that
was changed and it only took me 30 minutes as an untrained mechanic, so I
am unsure how it took you 2 hours.  I told him he was extorting the price of
the starter and it was not right.  He did not reply.  I told him not to do anything
more to my car and I would come have it towed.  
    In efforts to keep the relationship my sister has with her client kosher my
mom and sister convinced me to allow him to finish the work.   I did so and
today, a week and 5 days after the shop has had my car, my sister text me
that it was ready, however, I need to get a new battery prior to driving away
in it.  Shortly after my mom text me the same thing, but added he checked
for any electrical issues and found none other than it was wired improperly
by my friend and that is what caused the issue.  My mother also said I need
to get a new battery because the mechanic tested it and it was bad and I
should not try and jump it off rather get a brand new one.  
     I told her my battery is good.  I had it tested before replacing the starter
and after and it is only 2 years old.  She said the mechanic said the short
caused it to go bad because it was not holding a charge and tested bad.  I
told her that I did not understand because that does not answer as to why
the car would not start to begin with even after changing the starter, and the
harness.  She thinks I am crazy, which I may be.  That is why I am here
asking you.  
     I went and got my battery out the car to have it tested.  It tested good with
a voltage of 12.95 measured at: 669 CCA Rated:  615CCA temperature: 70
degrees.  I text my mom and told her was good and she says great your car
is fixed.  Go get it.  I do not think it is fixed.  Why would the battery test bad
while in the vehicle, but not outside of the vehicle.  Is there an underlying
electrical issue that is causing me to think the starter is bad and it got so bad
that it burnt out the starter and making the car think the battery is faulty?  
Should I follow my mother, sister, and mechanics advise and live under the
impression it was a bad install of the second starter and that is why it
happened again?  Any help is appreciated.