Press the Power On Button Once.
If this does not work, use the AC Power Supply, and then press the Power On button.
Always keep the AC Power Supply with you.
If you are using battery power, switch to a fully charged battery.
If the battery was fully charged, then you probably have a counterfeit battery.
These are common, so only purchase from a reputable dealer. If the price is too low, it is most likely a counterfeit battery.