http://support.radioshack.com/support_electronics/8186.htmCan you key in a medium wave freq like Pigmeat suggested?
I don't have one of those here. I have a 380 /San 808 it's from about the same time with identical controls. Mine goes directly to the band if you type in the freq and press enter. But I do remember the 390 maybe is different.
All the issues point to contact problems so unless you can get it working by some some easy means , frankly unless it's an obvious fix , there's little you can do.
The 808 I have has had multiple issues, honestly they are good radios but not surprised to hear of not working or fried
The buttons on the front are leaf switches and they are behind a rubber mat on the pcb.
Slide switches make the radio more affordable and for space reasons but opinions of those are not favorable . They do benefit from being used .