Terminated: unknown
The first thing one notices is how dark this calculator is. One needs quite a bit of light to see the markings above the keys. Quite a lot of pressure is needed to operate its keys. All in all not a great pleasure to use.
When numbers with exponents are displayed, only five positions of the number are shown, the last three digits are used for spacing and the 2-digit exponent.
The factorial operation x! does not have a check on the upper bounds of its input. The maximum factorial that can be calculated is 69! as usual for a calculator with a 2-digit exponent. However when one tries to calculate 70! which will overflow, it takes almost 6 seconds before the "Error" message is displayed. The larger the number the quicker the error is displayed, so it clearly uses a recursive countdown for factorials. It does error immediately on negative numbers though.
The EE key can be used to multiply any result or even the constant π by a power of ten. So, when the display shows the value of π, press EE 2 to multiply it by 102.