Reality checks:
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As your soldering skills aren't sufficient to remove a switch from the board, dealing with SMD soldering is likely well beyond what you should attempt.
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Current routers with greater capabilities are available for US$20 or less. Upgrading to 8M flash still leaves you with an underpowered, under-resourced router that will be obsolete and unable to handle current firmware reasonably soon (64 MB RAM on your W8970 will bite you very soon, 32 MB on the WR740N shown is already not enough for most applications).