Ronbeel,
Do you have leaves or signs of life?
Your zone may be a bit far north for tropicals. If you do, here are some items to know.
These plants were receiving chemicals that caused them to grow compact and have very abundant large blooms. The majority of wholesale nurseries that sell these varieties use this technique.
With pruning and pinching and proper feeding, you can recreate the effect 100 fold.
If your plant is leaf-less, you can scratch a small section of the trunk and look for green. If no green, it is likely the plant is dead.
Lately, you have a few options:
Either buy more, and expect them to die off.
Buy Hibiscus more suitable for your weather.
Be prepared to over-winter tropical varieties.

Hope this helps,
Ed