I looked at your post. (I bought the same white casing years ago). I still think it's a short circuit. It's only the keyboard light's left half that stays on; closest to the microusb plug. It started after I was plugged into an electrical system I imagine was installed in 1905. The whole system went goofy for a few minutes, I lost all battery power. Since I was in the wildeness I wasn't able to try to fix it for a few days later, so maybe there was some condensation buildup, but I doubt that (for no good reason except that the problem didn't dissipate at the rate water does). The keyboard light's on even when the keyboard's closed and whiie the device is otherwise off.
Fortunitally, with two batteries, a power cord fron and LG phone, low use, and bluetooth for file transfers it hasn't been much trouble.