I purchased a 48sx on ebay for $35 as is (from a surplus lab equipment dealer who didn't feel like testing it.) VG cosmetic condition I should add. It doesn't start and has a bit of wear in the bezel (someone obviously started it by pressing it there for a while to make it start). To make a long story short, it's not starting with a fresh set of batteries ( the battery compartment has no corrosion and overall condition is very good).

I've tried resetting with a paperclip with no results, shorted the battery terminals, and pressed in the middle of the bezel with no results. Should I try soaking in in dilute vinegar followed by DI and IPA, and let dry first? Should I go ahead and open it to install a new foam pad?

PS. I can probably access a sonicator if needed. Right now Im leaning towards soaking it in dilute vineagar, bathing in a few trimes in DI under sonication before testing it again.

Thanks in advance!