It sounds like a physical connection issue either in the USB nano-receiver or at the port. It could be that the nano-receiver’s connectors are loose or dirty, and applying pressure makes it sufficiently contact the computer USB’s port pins. Try cleaning the receiver’s connectors as well as trying a different USB port. You can also try to use pliers to '''slightly''' squeeze the top & bottom of the receiver so that it fits into a USB port tighter.[br]
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It may also be possible (though less likely) that a solder joint in the receiver has broken—applying pressure bridges the broken contact. That would require some careful board inspection and soldering.
You can also buy a new receiver for your mouse. Just make sure it’s compatible with your mouse model.