It well could be a flat tired battery. A battery should have a static charge of 12.3-12.8 volts; anything less it's trash. If you have a good battery, insure that the battery connectors are clean and tight. If all of that is OK, then one of the first things to do is perform an ECU code readout with a portable scan tool to see if any fault codes are set. The tool can be purchased at most auto parts stores. Post the actual codes here on the forum so that we may be able to help you further. If there is one or more fault codes set, they can help point to the malfunction.