Data will not be wiped from the unit when performing a soft reset.
If the Nexus 7 will not start, you may need to perform these steps.
Be patient as the Nexus 7 completes the hard reset process.
FAQ
Why is my Nexus 7 wont start or is stuck in a boot loop?
Try a reset after an hour has elapsed while keeping the gear plugged into the wall.
If that doesnt work, you may need to contact Asus for service.