Don't buy it. Reasoning: Never buy into problems.
Tern has a horrible record of frame failures on their regular folders. Seems they use the public as a beta tester instead of sound R&D. Not only that, but when the frame failures started becoming more frequent, the company tried to claim the bikes were being used past their design limits and therefore no longer under warranty. Double gotcha.
Now add an electric motor to a frame that has a history of failure. Bad idea. Increases the chance that your frame will split dramatically at any moment. Not the way I want to ride.