Please see video embedded below.
1. Firstly, you need to visit the Admin by Request portal - ABR
2. You will then need to sign in using your O365 account.
3. Once signed in Navigate to Inventory.
4. From here you can search based on user/device/model etc.
5. Once you have found the device you are searching for you can the navigate to Break Glass on the left-hand side.
6. Once inside here you can select the required amount of time needed for your break glass account and click "Generate Account".
Please remember to take a note of the details provided as you will need to use these to elevate every operation once signed in with your local admin account, I suggest taking a screenshot. Your time starts from when you first login to the device and not from the point of issue.