I'm sorry to hear that, Brandon.
I will grant that there are many different transformer designs out there, and some allow you quite easy access to the connections, with little risk of your having an "oops" moment.
Yet, the transformer that comes to mind when I think of an indoor transformer is the gray cube, about half the size of a desk. Those transformers typically have a sheet metal panel thet angles 'in' near the top. To remove this cover you must remove several sheet metal screws, then slide the panel up before you can pull it away from the transformer.
Since the panel lacks any handles or 'stops,' it's quite easy for the panel to slip down- putting the inward sloping part in contact with the windings. Or, when you 'rock' the cover slightly to get it out, that sloped part can easily rotate down into the windings. While I've never tried it, I doubt that the paper and varnish mixed in with the windings are very good protection against that sharp sheet metal edge.
Add to this the rather cramped locations where many transformers are placed, and it's hard to get a helper in there with you.
If you have any suggestions for removing these covers in a safer manner, I'm all ears.