Brian, can you please check the model number? The dmr-e225eb doesn't appear to be a valid Panasonic model. Could it be a dmr-ez25?
If so, then please unplug the device for 10 minutes, remove any connections to other devices, press and hold the power button for at least 10 seconds. This would be a good time to make sure that airflow to and from the unit is unobstructed by using compressed air to clean out any vents on the machine. A standard vacuum can also be used as long as you are careful not to touch any components sensitive to static electricity. When done plug the device back in to the mains. When you do that, if the problem is still there, please note if any error shows prior to it shutting down - the error is usually three characters (like U81)
If you'd like to venture into the unit to diagnose it for repair, the diagnosis should be fairly easy because this device suffers from a common problem, which is a limited lifespan to some of the capacitors on the main board, which could cause a number of problems. While it's difficult to test capacitance while a capacitor is still attached to a board, a visual inspection should be sufficient. Take a close look at the capacitors on the board, and look for leaking or bulging at the top of each. Here is a picture from this exact model:
You can see the faulty capacitor - the large black one to the left. If a capacitor is budging at all (this one is pretty extreme), then it should be replaced with one of a comparable rating. The rating for each can be found on the side - there are two numbers - one is voltage and the other is capacitance in microfarads (mfd). When replacing, you must replace with a capacitor of the same or slightly greater rating (slightly greater would be best - the initial failure occurs because the capacitor was not sufficient for the application).
These "electrolytic" capacitors are only one type of capacitor in the unit, but it is the only type that suffers from this problem, so there's no need to continue checking others. So, a visual inspection of the electrolytic capacitors is a start if the reset and cleaning doesn't help. If you still think that there is a fan problem, and it doesn't seem to be related to a capacitor, locate and check the fan to see if it's operating when the unit is turned on. With the device opened, it shouldn't overheat if that has been the problem. Try to recreate the same conditions as you had previously with the case on, turn the device on, and time as closely as you can, the period between powering up and when it shuts down. If the time doesn't change, or it changes only by a couple of seconds, then it is most likely an electrical problem or a transport problem (when the device checks to make sure the transport mechanism is free to move properly). At this point, the only course of action is to check the electrical components again or have the unit serviced.
Please let me know how you make out or if you have any questions along the way and I'll be happy to do whatever I can to help.