BLUF: There are just more questions than answers presently, including the game title in question.

It is difficult to miss a credit switch wired to a slam tilt switch, inside a coin door, if a potential buyer has the chance to review high resolution photos. I have seen shunting done for other purposes, but once again I do not know the title, year, or manufacturer.

No one can have any idea, what if anything was checked from either party regarding this situation.
Every game has to be inspected fully upon arrival, not just put the legs on, drop a ball in, and turn on the power.
This looks like it occurred.
This is incredibly common, and incorrect startup procedures, as people forget to validate.
Even NIB games need to checked, but rarely private owners actually do what operators have done for decades.

An example:
On my EM Fireball (Bally, 1972) I had caramelization of the solder points lugs on the transformer which prevented the entire game from getting proper reliable power on receipt of the game. Conditions were "flaky". Resoldering after cleanup and full solder removal fixed the problem after diagnosis, but I could not blame the dealer, as he did not miss the problem, as it did not manifest itself. This was a very rare problem, most have never even heard of before which is entirely age related of a 45 year old game.

I and many others have done business with Jeff for over 20 years and about half the time I been the hobby in general.
I have not a had problem regarding service or products.
In fact, I just got another set of stencils less than month ago in under three days.
I can state others have had problems with his stencils, but much of it has to do with cabinet preparation and proper use, not materials or construction. Some simply do not read directions.

From experience I can share that transport of games can cause issues, especially if the electronics are not inspected in very early SS games, but not complete failed electronics unless there are grounding shorts, a game is dropped, or an owner reconnects the game improperly. I am omitting uncertified hacked repairs from this circumstance.

Maybe this would be an opportunity to learn some pinball restoration skills?
Buyer beware applies to every single pinball purchase.

BLUF: This helps you to learn to troubleshoot and diagnosis game problems.

This will allow you to more expertly evaluate games and there original condition during the buying phase.
This will assist in teaching you what to looking for in the most common transport problems.
It also significantly reduces external repair costs.
Everytime games are shipped there is risk of vibrational damage, especially older SS titles due to the age of components, cold solder joints, and wiring.
A complete host of advantages.

Here is a very key point that you may not realize.
You list ownership of a fairly robust diversity of titles from a multitude of different manufacturers and eras whose designs are not identical.
However, many of the titles listed are less than two decades old, which is also very relevant when it comes to reliability of electronic components, integrated circuits, and semiconductors.
Maintaining a large collection can be expensive in the long run if a person does not know how to fix small problems.
Essentially problems compound over time until games become totally non operational.
More expensive than the games themselves, if an owner is paying someone to maintain them, and IF the technician is truly experienced, does not overcharge, and knows the manufacturers.
"Bulletproofing" old games is not repairing games (although it should be), and technicians that come out to fix games do not normally do this as is generally part of the restoration process, unless the technician does this out of his gracious support.
I have met people that are very savvy with one manufacturer, but have no idea on others, and it sometimes makes a big difference regarding game logic design of solid state boards and power supplies.
Some repair aspects are synonymous, some are not.
This is not case when it comes to EM games, even the score reel assemblies, except in a few rare unusual manufacturer cases.

I never expect people to understand how to do everything overnight, especially PCB repair, but basic repairs are essential.
I have seen this happen many times with other owners who become increasingly frustrated as more and more games they own stop working and eventually get out of the hobby entirely.
It simply becomes overwhelming, and they sell out.
I don't want that to happen to you, and I "spider sense" things.

The comment was not meant to be negative.

BLUF: The more I read this thread, the more I continue to suspect new owner inexperience.

Very unfortunate, but has become common today.
This is part of the reason certain brokers will not even sell project games at times.

It's a new generation, and times have shifted, especially when someone does not recognize the value in learning why it is important to know basic repair and troubleshooting.

Money does not fix everything, but people with repair skills do.
Attacking long time collectors/restorers offering respectful advice, does not win friendship or support. There was one thing noted correctly. It still is a very small hobbyist world in pinball. Most of us do know each other. Something to consider before publicly berating anyone.

If people are consistently unhappy, the only real solution is to do the restoration work themselves and figure out their problems on their own.