Welcome to Just Answer.
Sorry to hear about your problem.
The F70 error apparently is a design flaw that happens to many of these machines in this series (HE3t, HE5t). It has something to do with a failure of the components to communicate with each other. The main circuit board most likely needs to be replaced. If this is still under warranty or you have the extended warranty, take advantage of it.
If you need further help or clarification on this answer, please do not hesitate to reply to this post.
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Best of Luck, Brian
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