Not sure if they'd let you pick things that have been dumped, but I might check out the electronics recycling center section at the Cambridge recycling center on Hampshire St.

Charles River Speedway is definitely worth considering.

Sorry for your situation, that sounds frustrating.

This doesn't feel like the best place to ask this question though given that it's not about turkeys, dunkies, the T, or bicyclists.

I'd suggest posting in r/HomeImprovement to get started on what you should look into.