How To Possibly Revive a Magic Mouse That Won't Turn

Hi. Assuming the Magic Mouse don't have lose connections inside from falling hard and the contacts are good, including the rechargeable or non-rechargeable battery; if you have a Magic Mouse that's out of warranty and won't turn ON, one way I revived mine was to put it in lots of layers of quality static bag and foam (I've collected more than 10 when I used to assemble my PC before going back to the Mac) with lots of absorption gel in it (batteries not included; absorption gel, around more than 15, collected from food items over the years but it's available in stores). Switch it ON and click seven times or 12 to get rid of possible static (this is similar technique used on a PC when it's not powering ON) before putting it in the layer of static bags with the absorption gels. Test it with a newly charged batteries or if it's non-rechargeable, make sure it's still has sufficient power by using an electronic tester or something similar or buy new batteries.

I got to revive it, maybe because the problem was both moisture and static which could be related (plus the mouse is 3 and half years old).

If it doesn't work try to put it in that bag for a day or two. If it still doesn't turn on after that, you may have to open (using the guide from disassmbly sites like iFixit) to resolder the solders in there, some connections may be lose if you've been gaming hard or using it hard (or it fell hard).

Also be sure if you use rechargeable batteries, that the batteries still charge well and make sure your Mac's bluetooth is not the culprit.

I hope this helps.

God bless.