I'm focused on the door. It's not locked, but you need to ring a bell for someone to Buzz you in... and inside everyone wears ear protection to avoid the loud sound. How is the button press from the outside signaled? My question then turns to the "ring for buzz in" set up, where the door would unlock and open up from a buzz in. If this sign was in place and the plaintiff opened the unlocked door, the assumption that the door was unlocked by a buzz in could reasonably justify plaintiff's entry into the shop and subsequent exposure to the damage. I would also question how safe the shops set up if a simple fall from a broken high heel shoe could cause her to fall in a waste disposal unit right by the primary entry/exit into the shop. While the floor may have been incompatible to her shoe, people can trip and fall just as easily without a stiletto. Suppose someone wearing proper footwear because of untiled shoelaces... they would have befallen the same fate. A common wisdom would be to move the waste collection away from the entrance and have lid or barrier to prevent a tripping person from going into the bin.
Furthermore, they the placement of a crane operating tool so close to an exit that a person blinded by the fall would grab it and accidentally press the release is still very haphazard placement.
Having passed an OSHA safety compliance inspection will not immunize you and there is no documentation that the inspection was conducted with all equipment in places where they were on the date of the incident. Additionally, the lack of a closed gate into the loading/unloading or any clear signage on the drive up is worrying. You mention that there is a gate preventing traffic into the area, but it's left open for convivence... this line of thinking has lead to many a disaster failure and the purpose of the gate, as implied by OP would lead me to believe it's purpose was to deter traffic from entering a restricted access.
The door being unlocked for fire safety concerns is not an excuse. Emergency doors that open from the inside is a critical feature in many buildings that have to consider an evacuation but require patrons and employees enter through a restricted area of access. These types of doors are installed in movie theaters for example, so that guests can exit the building but not enter to avoid paying the price of a ticket. You could even have doors that do not have handles or knobs on one side that would allow for exit but be impossible to open for entrance.
What it seems to me is that plaintif drove into the loading area by mistake because the gate was left open for convience, thus defeating the purpose of the gate. The plaintiff then parked in the loading zone and went to an entrance that allowed her to ring a bell for a buzz in. The workers inside, due to their mandatory ear safety, did not here the ring and there was likely no visual indicator... if there was, the visual indicator went ignored. Never the less, the Plaintiff, after being ignored, tested the door and found it was unlocked. It would be reasonable to assume the buzzer was not working... upon entry, the grate broke her shoe, causing her to stumble and fall into an uncovered waste disposal unit where she recieved injuries to her face and eyes. She was able to extricate herself from the unit and in her blindness, grabbed for something to use as leverage to return to her feet. While in pain, she grabbed the crane operating controls and pressed a release button, which dropped it's load, causing her further injury as she was struck by the load.
In this situation, I would certainly find that the metal shop had multiple different ways to prevent the entire situation and question the claim that the shop was OSHA compliant at the time. They could have stopped the car by keeping the gate down and direct them to the parking lot and front office which would handle the Plaintiff's business. They could have made the door lock from the outside only, preventing the plaintiff from walking in under the presumption that she had been properly admitted into the shop. They could have kept the equipment that lead to the injurys away from an entrance and if not impossible, had it properly covered so an innocent trip would not result into falling into the waste face first or place the crane operating cable in a location directly under the crane's load. Or left the crane unattended in a loaded state.
What's more, in a real case, the hostile nature of thethis post (referring to the victim in a derogatory term and refusing to consider her injuries or as purely her own fault and calling her a rule breaker despite ignoring the multiple points of failure, any one of which, would have prevented the injuries. In fact, it makes the defense seem like they are more inconvenient because of a work stoppage and a blocking of their loading docks, than a woman who was blinded in an accident. In fact, the detail that she parked in a loading dock makes it seem like you were inconvenienced because you had to have the car towed before you could load trucks with your goods. You offer no evidence that her "trespass" was in fact malicious or that her reason for being on the property. A sign alone does not absolve from failure to ensure that safety of workers and customers is your highest concern. In fact, the fact that you think it does and thus you're not without fault is alarming for someone in such a dangerous industry. The attitude you took in your initial post will not win sympathy from a jury.
There is no way this gets dismissed (it is not frivelous and it does hold water. Dismissals assume that the facts of the case as presented by the plaintiff are true when considered, which would be grounds for the case moving forward. A summary judgement occurs when the plaintiff and the defense agree to the facts of the case, which she likely contends that differntly). It will likely go to discovery and if no settlement is made, I doubt the OSHA people will be the shield you think they will. I would love to see your company's OSHA compliance safety check and see the lay out on the date the check occurred vs. the date of the incident.
All things considered, it is probably in your best interest to settle and pay her medical bills, because there is a cap on compensatory damages that she can win in court. However, there is no cap on punitive damages, which are there to punish because the compensatory damages are not enough. I'm sure they will seek punitive damages, and I would see your lawyers having a hard time convincing the jury that they shouldn't grant those damages. If you can avoid a trial by paying medical bills alone... that's a win.