I think I just did a stupid thing.
late last night I was trying to resurrect a 48SX that had/has a battery acid damaged keyboard.
I have a 3 cell batter holder to test the unit before putting the back on. I think I reversed the polarity of it and momentarily smelled overheating electronics before I pulled it. Prior to this, I did resuscitate the unit, but the LCD screen had lines (I hadn't tightened the clips).
Is it permanently dead? I've read doing this will fry the zener diode. Where is it? Can I replace it?