Hi,
why an ASSR? You don´t need isolation. But it draws much (battery) input current. The cost is high.
There are dedicated power swtiches. With the features (depends on type) that a power switch needs: low supply current, short circuit proof, dV/dt limit, low ON resistance, maybe even power limit.
The right circuit makes no snese to me. Why paralleled resisitors? Why the high ohmic voltage divider? Why paralleled capacitors? 10pF makes no sense at all. .. At least without additional information.
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To your problem: Drained out battery? Did you check battery voltage?
Klaus