Can you hear pressure or steam escaping... a hiss? There is a "floating" valve on top that must be pointing in the correct position or it allows all the steam to escape preventing pressure from building. On most units you must set the function and the time, then press "start".
They're really very simple. Would it be possible for you to post a photo of the front panel of your unit? Do you have the instruction book?
New Mexico☀️Land Of Enchantment