Trickle Charging it caused something do go really wrong with the display circuitry and over half of the screen was randomized color-static looking garbage. The phone itself seemed to operate fine, but the display issues rendered it useless.

I later learned that if you use a portable solar panel battery pack, let the pack charge and then plug in your phone. Don't plug a near-dead solar panel battery pack into your phone and let. There's something about the low-voltage trickle-charge that can be terrible for electronics. I'm not an EE, so I don't understand the details. Perhaps someone else can explain it better.