I don't have a very good explanation of how this happened, but I brought an Eton E100 back from the dead. This particular E100 (based on the Tecsun PL-200) has had a rough life. I bought it used, and kept it in my bathroom. So, it endured humid conditions due to the shower and a weak ventilation fan. And it went through a few gravity incidents.
At one point, it would act very confused when powered on. The LCD would show corrupt or blinking characters, and no sound was produced. I couldn't tell what band it was on, and the numeric keypad, up/down buttons, and tuner knob weren't responding. I removed batteries for lengths of time, tried different sets of batteries, tried the reset switch on the bottom, and nothing was working. So I took the batteries out and stuffed it into a dresser drawer to be forgotten.
I saw the radio again a few days back, and wondering about radio electronics, I opened up the case to look inside. Everything looked normal, except for a large capacitor that showed evidence of leaking. When I reassembled it, I put in two batteries just for fun. When the radio powered on, it started...behaving normally! Honestly, I didn't make any internal modifications more extensive than gently removing a small amount of debris. I'm not taking any credit here; this E100/PL200 has crazy super self-healing powers. Honest.