/ Warm Reset:
Hold the 'Power Button' for 2 seconds, this should cause a menu to show, here you have the option to reboot.
/ Cold Reset:
Hold the 'Power Button' for 12 seconds, this should launch a forced reboot.
The Power button can be located on the right side of the PDA.
If the problem persist, give us a call on +45 78 768 555 or write a mail to firstname.lastname@example.org.