Maybe a dumb question, but what would be the indicators that we have found the bottom?
Not a dumb question at all. Fundamentally, I'd expect to see consolidation in the price levels. Consolidation is when there is a lot of trading in a very narrow range. So after this big drop, I expect silver to bounce around a while wherever it ends up. The traders with losses have to be weeded out psychologically before new bulls can come in.
Indicators are secondary to price action, but I like to look at a series of moving averages (including MACD), volume trends (actual volume and OBV), ATR, and various oscillators like RSI.