Editor loading stuck at 92% on Spirit using Theme Test Drive

With the patience of a still mountain overlooking the sands of time, I have waited. But the editor for my Spirit theme won't render past 92%. (I let it sit and spin for 2-6 hours over multiple attempts.)
I've disabled then reactivated all my plug-ins. I've rebooted my computer. I've done many things, yet to no avail.
How, oh, how, might I create my website using Theme Test Drive?
Please help.