Magic Mouse 2. Be sure to keep the utility open while pairing and during its use. Tried everything, even buying a new MM2. There are many adapters out there that have been proven to NOT be compatible with the Magic Mouse.
Click Update Driver Software and then follow the steps in the wizard that appears. The Magic Mouse and Magic Mouse 2 have a slide switch on the bottom of the device. To unpair it, choose Apple menu > System Preferences, then click Bluetooth. This is not true. Go to device manager. I have to the same situation.

Back when I initially pointed out this issue with the Magic Mouse 2, Apple contacted me to note that the device could suck up a full day’s charge in just two minutes.

I would reset your SMC then your PRAM in that order first: Reset the System Management Controller (SMC) on your Mac. Go to device manager.
It sounds like your computer acknowledges that the Magic Mouse 2 is plugged in and seems to be trying to charge but the charge number never goes up. Take this as a warning if you decide to buy a different one.

Earlier wireless mice. On the Magic Mouse 2, green coloring is visible beneath the switch. The serial number of your Magic Mouse 2 is on the bottom surface of the device, along with other markings. However, the Magic Mouse 2 (with the Lightning port for charging) does not have a green light or pairing mode. Connect the Trackpad, make sure device's power is on, setup using Bluetooth section of System Preferences. Here is the Apple support article with the steps I described: Set up your Apple wireless mouse… You can find the serial number of earlier Apple wireless mouse models inside the device's battery bay: Bluetooth Won’t Connect Your Magic Mouse 2. Click Update Driver Software and then follow the steps in the wizard that appears. You can charge these devices by connecting them to a Mac or a USB power adaptor using a Lightning to USB Cable. Then: How to Reset NVRAM on your Mac. With Magic Mouse Utilities and a Bluetooth connection, Windows 10 owners can use the Magic Mouse 2 on their desktop or laptop. You still need Bluetooth. iPad Pro 12.9” It will only show when the mouse is plugged in via Lightning to …

The problem wasn’t the mouse itself but with the Bluetooth connection on my iMac. Press Windows + X key on the keyboard. Incompatible or not properly installed graphics card drivers are the most common cause of this issue. 1st of all, I have to correct myself - the mouse is an Apple Bluetooth MIGHTY Mouse (not a MAGIC one).

With Magic Mouse Utilities and a Bluetooth connection, Windows 10 owners can use the Magic Mouse 2 on their desktop or laptop. Magic Mouse 2 (rechargeable batteries) did not work for me. Step 5: Pair your Magic Mouse 1 or 2 with your Windows computer via Bluetooth and enjoy. Apple doesn't support this combo. Step 2: Follow the steps below to update the touch drivers.