I bought a second hand
Baking soda will nuetralize the chemicals, but will not clean the contacts sufficiently. You will have to use a fine grit emory cloth or knifeblade, or similar abrasive material, to scrape the compromised contacts, until you get to fresh, uncorroded metal underneath. This will usually restore the unit, and make it operational.
Also check that the switch is good for the light, since they can become oxidized also.
If you're good with a voltmeter, you can ohm out the wiring, or troubleshoot it to find the problem.
If it's a switch, it's usually a swivelling metal contact, so make sure it's clean and making a good connection.
Good luck, and hope this helps.
