If you have UV burn on your face your shield was not in place.Its that simple. A shield with an inoperative lens ,or not(due to battery failure ) cannot pass UV rays. Its a solid sheild. UV rays will not transmit through the lens,operative or not.Its pure physics.
Its fairly obvious that your shield was not in place for at least some of your arc time anyway.I would hazard a guess and suggest you may have been spot tacking without the helmet.I have been guilty of that too and paid the price you are paying.
I didn't have one in place, I was welding piano hinge tabs (about 1/4 wide tabs) kinda hard to hit that when you can't see, which is why I was upset about the dead batt.
Welders are always advised in OH &S instruction to wear safety glasses.A pair of clear plastic safety glasses WILL STOP transmission of the UV rays to your eyes.
I did not know this, my normal glasses probably magnified the UV rays
I have checked that statement with my own ophthalmologist and he confirms it.Wearing safety glasses under my helmet I have not had a flash in years as I have had to wear prescription (safety) glasses under my helmet to achieve decent vision.
I have been kicking backsides in my classes for 30 plus for those that are too smart to wear the eyeware PPE.
For pain relief go to the ER .
I don't like visiting my mom at work, she gets mad at me when I see her there.
Cheers
Oz