That explanation of the fear makes a lot of sense. My first piece of advice would be to make sure that it can never happen by accident. Make sure that the door is propped open or that there's something blocking the latch so that she couldn't accidentally be locked in again. This is important through the next steps as you work to desensitize her to it.
Next, if she's comfortable going in the room so long as the doorway isn't blocked, I suggest setting up space so that you can feed her in there. While she's eating, make sure that nothing happens that would trigger her fear. If you can, consider moving her litter box into that room as well. The goal is for her to spend enough time in it that all the previous negative associations are overridden by the boring-ness of the space.
Monitor her behavior in the room for a few months. Hopefully, she will start spending more time there and you will see increased comfort without any other changes.
Once she seems quite comfortable in the setup, start very gradually pushing on the fear. You mentioned that if someone stands in the doorway, she will bolt. Some days as she's eating, start coming and going from the room, pausing for a just moment in the doorway. The goal is to find the spot where she notices and just starts to tense up before you remove the threat. You never want to push her to the point of bolting, as that will strengthen the fear response. Instead, you want to habituate her to the stimulus so that she stops even noticing it.
Once she doesn't seem bothered by brief pauses in the doorway, start making it scarier. Lengthen the time that you wait, take up more space, have someone else briefly block the doorway, etc. Again, you never want to push her to the panic point. Be prepared for that "panic point" to change day to day. If your work is helping, it should slowly get better; she should slowly be able to handle more and more. However, some days it may seem worse than the day before and that's okay. It will depend on her mood, how rested she is, if she's had enough exercise, etc.
When she's okay with people in the doorway, start introducing objects blocking it. You might put a chair in the way, or a baby gate, or a box. Anything that you have lying around that she can jump over/climb through and that won't cause a safety hazard for the humans that have to step over it or move it when they need to enter. When you introduce an object like this, keep it there for a few days at the beginning. Make sure to put it there when she is out of the room so that she can investigate while she enters. After she understands the object, you can take it away and put it back periodically while she's inside. Watch her response carefully and make sure that she doesn't reach the panic point.
When she's okay with miscellaneous objects, try leaving the door partially closed. Follow the same slow process as before where she gets to explore entering with a door that isn't fully open before she has to leave through it. Eventually, you should be able to close the door while she's in the room without her panicking.
Best of luck!
