No, no magnetic fields.
I'm fairly certain that the display on this phone has just failed. I returned it to my vendor, and it plus some cash will get me another, most likely refurbished, unit.
I went though the several spares that I have, and found two that I'd rotated out for the washed out screen problem. However, when these two powered up, after the initial splash screen, the screens went very dark. This happened, I'm guessing, because they'd exhibited the wash out problem, and the users cranked the contrast to its maximum to make them readable. I was able to restore them to readable by decreasing the contrast to mid-range.
When they exhibited the problem, I tried unplugging then immediately re-plugging to power cycle them, but they always returned with the washed-out display. So, I rotated them out with spares I had, and left them sit on a shelf. Now, they're fine. Not sure what to pin that to, but I felt the details would be worth sharing.