UD Pocket works on systems with BIOS and UEFI.
It is essential that your system supports booting from USB storage media. This may already be enabled, or you may have to enable it yourself. The required key presses for this may vary from vendor to vendor. However, here are some hints:
While the device is booting, try pressing [F12] (in general), [F10] (Intel devices) or [F9] (Hewlett-Packard devices) in order to access a list of boot devices and select UD Pocket.
If the above does not work, access the BIOS settings via pressing [Del], [F1] or [F2] during boot and activate booting from USB storage media and/or change the boot order.
See the BIOS/UEFI documentation for your system for details of how to boot from USB storage media.
As of version 10.04.100, IGEL Linux supports UEFI Secure Boot. Refer to the manual of your device's manufacturer to learn whether your device supports Secure Boot and how to enable it. Enabling Secure Boot often consists of two steps. First, the boot mode has to be changed to UEFI Boot in the BIOS; after that, Secure Boot can be activated, also in the BIOS. How to check whether Secure Boot has been properly enabled you can learn here.
If UD Pocket fails to boot in UEFI mode, try it in legacy/BIOS mode.
Do not remove UD Pocket from the computer until you have shut down the IGEL Universal Desktop Linux contained on it. Otherwise, you can damage the operating system on UD Pocket and lose your settings as well as data on other removable media.