You may try all that (bending/cleaning; spring trick; oven heating) but in the end it wilk hapoen again. This is -beside the well known USB fall out- the most happening failure of this device.
It happened to me all 2-4 years of usage. And I have three of them stored away and one (which is not that bad but probably same as yours) for nostalgy still charged and reachable...

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SIM change will most probably not solve this