If you are unable to install Windows Updates because you are below 40% and the battery will not charge above that you can do the following. This will remove the battery temporarily and Windows will allow you to update.
Step 1: Plug in your Surface.
Step 2: Select the search box in the taskbar, enter device manager, and in the search results, select Device Manager.
Step 3: Select the arrow next to the Batteries category.
Step 4: Double-click Microsoft Surface ACPI-Compliant Control Method Battery, and under the Driver tab, select Uninstall > OK.
Step 5: Install Windows Updates.
Step 6: Go to Start, and select Power > Restart.
Restarting should reinstall the battery driver for you.
Depending on how many pending updates you have, the steps above may need to be used multiple times.