Ya the Park ave did it to me tonight at gas station.
"Excuse me Sir, Can you help me to get the fuel door open, so I can get some gas in this thing? "Sure the man replies: What do you need me to do?
I replied "hold down the electronic fuel door release button, while I pry the door open"
(There is a joke in there- how many guys does it take to open a fuel door??)

So lets back track to yesterday when I got off work. Find fuel door open at PA?
WTF why is the fuel door open??Go to close it wont stay closed. Ok me clueless.
Out comes WD-40, spray the snot out of the inside release latch, beside fill neck.
Spray release switch as well. So nothing seemed to help the fact that the door would not stay closed so I bent metal piece inward on door that contacts the release, so it would now stay closed.

Lesson learned- the WD-40 overnight must have worked into the gas door release pin.
Although it only monetarily releases it back when you hit button, because I had bent the whole thing inwards it had locked the door still in place.
The pin is suppose to work where it stays out until you hit release button, then it retracts. It had stuck backwards, which is why it would not stay closed.
Anyways I got it back working, as long as this pin functions normally, by re bending the doors clip back inward to make a lighter contact against the pin.
Good God I know this is long, am wondering if others have had this problem with their gas doors???
It looks like replacement of the lock mechanism may not be pleasant either, anyone know on diagram or how the lock solenoid is replaced ? Is It riveted in there?

I am somewhat surprised you didn't utilize the manual release in the trunk. It would have at least saved you the humiliation of having a helper press the button.

On the subject, were you looking in the trunk with replacement in mind, any insight?

Ok I just checked the owners manual! There is a fuel door release,inside trunk THANKS!
No I have not peeled anything back inside trunk yet. I was hoping for some info from an FSM on replacement if possible, or maybe someone has had same problems with this electronic latch sticking closed or leaving the fuel door always open.

When mine wouldn't open it was the push button switch in dash that was the problem, replaced that, fixed mine, which wasn't opening at all.

I have not seen mention of this issue on the forum before. Not to say it never happened, or someone didn't post about it, but I have never noticed one.

I guess the proper word should be latch stays retracted, leaving door open.
Ya my luck it is well worn & on the way out.
As long as I keep some WD-40 on it it works now.

You might want to check for that cable release in the trunk and make sure it isn't hooked on some thing and keeping the door open. the cable could keep it from latching if it was hung up on something.
If the electromagnet switch was bad like mine the door latch won't open but always closed now I've hung that cable up an the door pops open an won't stay latched till it was hanging free again. had that liner in an out a few times too many. With working on the fuel pump and this door latch.

Ya TJ will check out the pull cable, but in my case I do not think it is the cable as it was staying open. I also will have to redo the whole fuel pump too one day. When fuel is lower or just slightly below half a tank, the fuel gauge starts going crazy, going from empty to full swings. Not on the priority list right now as I keep tank full. I am saving for a new Gm rebuilt 4t65E trans to go in this year. I can see this car is like many woman, high maintenance!

My 96' is the same way, if I do not have WD-40 on me a lil spit seems to work, hold the part surrounding the latch and try to move it to see if it is loose, mine loosened and moved a bit, so that made it stick even more.
I'm not sure how much a new latch would cost for your PA, but it is about 28.00 for mine at nalley buick parts..

"I am saving for a new Gm rebuilt 4t65E trans to go in this year."

I was just looking at a L32 Series III and tranny for 2,200, I really cannot afford it, but I'd love to get it and learn what I need to so I can swap in the motor myself, I already know how to disconnect/remove most of the stuff, I just need to learn a few more things, and get a few more tols.

Why do you need to swap the motor & trans ? High mileage problems or what?
I thought these engines easily go to 300K.
I only have 84 k miles, luckily. The trans, I might as well swap in new one instead of just a rebuild mainly to valve body as the ole P1811 code is not good etc.
Anyways, back to the locking situation, I have thrown another dose of Wd-40 in there and pin slides easily back and forth now. Hopefully it hangs in there and wont need replacement.
I also checked in the trunk today. The cable and tag was ok and works, but I used some double side Velcro to hold it up and away on trunk liner. If it does not hold, I may just drill a small hole in the tag and use a safety pin to hold it onto the liner, so there is no possible way for it to get caught on crap in trunk, and possibly open the fuel door.