Just to give an update for anyone else who has this issue...
Contacted customer tech support. They had me remove my battery completely, along with the SIM card, and leave it out for a minute. Before putting it back in, he had me hold the power button for 5 seconds to drain any remaining power it may have still had.
He then had me put the phone back together, hold down the Home button and the Volume up buttons, then press the Power button until I felt one vibration. Then he had me let go of the Power button. The recovery screen popped up and then he had me release the other two buttons.
Then he told me to Data Reset, press Power to select. Next screen, using volume buttons to scroll down, I again pressed the Power button to select "Yes, I want to do this." The phone then went through the data wipe (on it's own, the cache was included).
The rep then had me reboot. This time the phone came on, along with the T-Mobile jingle (that hadn't happened previously) and within 2-3 minutes, it had booted completely up to the Language selection screen. Whew!
Thank you so much, Vernon in Colorado!!