Magic Mouse Sticks in Full Clamshell
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Found this discussion which strongly suggests it is a hardware problem but not the mouse itself. One guy solved it by using a USB dongle.

My original answer remains below, un-edited.

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Never had this problem w/ my magic mouse, nonetheless...

Get back to a default - disable any 3rd party enhancement software. Reset mouse system preferences to defaults.

Magic Mouse iFixIt video search

From there, Here's an interesting video: Can I DYI fix a Broken Left-Click Resistance?. The tear down may not be something you want to do. I think I would try because the mouse seems pretty useless in its current state. iFixIt sells tools and parts for doing this kind of stuff.

P.S. I liked my magic mouse perfectly fine. In the PC world this thing is E.T. alien technology. Anyway, I like using the magic trackpad much more.