Press the reset button and the machine will restart. Press the on button quickly and don't release it until it enters the ce desktop.
However, because this way leaves a back door for the machine, many machines do not leave this back door, and each family will do it slightly differently.
If the computer has an interface to run the programs in the SD card, it can be done. It is generally possible to replace the previous program name with wince browser, but this way is to enter the browser, not the desktop. Actually, this is ok.
To boot to the desktop, you must first modify the registry to boot the desktop without activating the original interface. This can be successful if there is a browser on the machine. If there is no wince browser on the machine, it can also be placed on the SD card or built-in flash, but there is a premise that the SD card must be recognized normally before starting the browser, and some machines may not have this.