Today I could complete the restoration of an Epson HX-20 I have got some weeks ago on willhaben.at for free.
The first inspection resulted in some damaged capacitors and a missing battery pack. This ended in strange behavior because the device doesn't work correctly if the internal battery is missing, even if it is connected to an external power supply.
There is one interesting point, that could be helpful to others too. Some parts of the memory is always turned on to keep time and stored programs. Sometimes this memory gets confused and needs to be reset. This happened if you see strange characters after turning it on, or you don't get to basic from the start up menu. Firstly I thought one of the ram chips is damaged. Normally this reset is done by pressing CRTL+@. My device has got a germen keyboard layout and there is no @ sign. On my device I had to press CRTL+§ (Control+shift+3)
p.s.: Like on many other 8-Bitters from the 80s like the C64 and C128, the basic is from Microsoft :-)