smoke in dash

[Randha]

Hello there,I am Randha,and owner of a 986 1999 2.5 boxster (excuse for my writing),i purchase the car 2 weeks ago,next thing happend,battery clamp was a little bit lose,when i bought the car.but i didn't know it.
next day when starting in the dark,i switch the light ON and start,suddenly every thing was black no power, before it makes the turn,i quiky check the battery and found negative is lose,so i turn it to make good contact(didn't.have any tools),and every thing works,so i thought,but all is reset to zero after checking the cockpit display,i start the car and and saw the light was on but no cockpit light!,i had a appointment so i have to go,about 15 min driving,after the apointment i start the car is runs great,i switch the light on,and suddenly cockpit light dims and complete black,and than the horrible plastic smel and smoke on the dash behind the cockpit,i shocked because of the smoke,i quicky disabled the battery.wel end of porsche story in my mind.

after research,light switch i a common issue,but saw now one is commenting about smoke that can catch fire in the wiring.wel i did some testing without switch,no smoke runs great
with switch then smoke,

conclusion switch is no good,i ordered a new lightswitch,
before placing can any body tell me,where to look for damage wiring?,because i check beneed the dash,and couldn't see any damage wiring,but the smoke has to came from somewhere!!!,the only thing i guessing is to remove te cockpit,before i do that,i want your opinion what to check!!! thank you every body.