Electrical system malfunction

So I just started a 3 week deployment in Japan, and my wife is having issues with her caprice.   She'll drive her Sky in the meantime. It seems like house problems like gas leaks, roof leaks, water heater failures and other vehicular malfunctions stuff only seem to happen when I'm away with no possibility of dealing with it myself.

She initially told me the rear passenger courtesy light was staying on at all times, and that the on/off switch had no effect on it.  After asking her to just pull the bulb she told me the issue was resolved (she didn't get to pull the bulb) but that now a check gauge (I assume the CEL) was on in the dash.    Never had a CEL in the caprice. I thought it wasn't a big deal and that I'd scan it with datamaster when I get back.

Later today she send me a pretty angry email saying she heard a loud "pop" while driving (which she described as coming from under the hood near the floor), and lost power steering, power brakes and turn signals, and that the radio and dash "went crazy," which probably mean they were flashing.  She was able to get the car immobilized safely and didn't hit anyone, but apparently it was close.  She said a policeman called a tow truck for her and it was towed back to our place.  Now the car doesn't start.  Apparently all the dash lights are flashing when she tries to start it.

Car history: Car is a 95 caprice with about 70k miles.  In the last 4 years I have not observed any bizarre electrical occurrences on this vehicle. It has the brass aux terminal, Innovative Wiring battery cables.   Battery is a one year old Kirkland, alternator is AC DELCO 140 A unit.  I installed it max 3 years ago to replace a whining 105A unit, however I did NOT install the brace from a 140 A car.  Recently, I installed Roadmaster limited seats in the car, which required splicing into the electrical harness located under the carpet.  Additionally, on the day before I left, I changed the Fuel Pressure Regulator with a known good unit trying to resolve a long crank on start issue.  I then drove the car for over 30 minutes.  My wife drove me to the airport on the day I left, and it was running fine.  Those were the last 2 maintenance actions done on the car.

I won't be able to look at the car for the next 3 weeks.  The popping noise makes me wonder if the tensioner fragged or belt snapped (not sure if that would explain the loss of brakes though).  I realize this is very little information to go on, but any ideas where to start looking?

Guys, not trying to be a one track mind here but think, what switch get's used every time you start the engine ? I have had to replace the ignition switch on my 96 Estate Wagon already and have had to replace every one of them in my fleet of Lincolns. Many short trips caused more use and quicker replacement than on the cars going long runs on the highway. I agree that replacing that ignition switch is a humorless job but they do wear out. You seldom hear backfires nowdays but that may have been what your wife experienced. Our cars are getting older and will need consumable parts replaced to keep them reliable. No different having to replace brake pads or belts. Hope you have an easy fix !

Fixed. The AC Delco alternator had failed. It was a new unit from Amazon. It lasted just over 2 years, but under 5000 miles.

Not sure if it's in any way related to not using the 3rd brace.

I threw on the old 105A I had lying around and the car works fine.

On an unrelated subject I found the EVAP solenoid line had melted on the passenger side manifold while I was gone, which explains the CEL she got. Spliced in a new piece of line.

You are fortunate that it was a simple fix. It is too bad that women in general are not taught vehicle maintenance. They tend to rely on the men in their lives, and assume that the only thing they have to do is put gas in the car and drive. If it breaks, they freak out and expect the guy to fix it. If he is not available, they freak out to a higher level until it is fixed.