OP here... Thought I'd better update.
I tried calling and leaving messages with DRwireless, but got no replies for a few days, so I'm not sure if the numbers on his website are still correct. I finally sent him a message through his Ebay store, even though he didn't have a listing for a remote reflashing service. He did respond, and after several questions to each other he determined he could do it, but I would have to find some good internet speed for him to be able to remote flash it. This became a problem as the park we are in doesn't have good speed and even tethering from my phone was marginal. We also had a rough time finding time when we were both available and our messages being handled by Ebay were taking about an hour between each one.
Once we did get a time to work together, I of course couldn't get much signal but after several text messages and walking me through it, and several retries, the Mi-fi got reflashed, and is now working again. I also got much better instructions on how to keep the Mi-fi healthy and also how to check the time remaining and how to refill it and some websites that work for $5 cards.
All in all it was a little frustrating for communication, and the fact that on my end I was having difficulty getting a good connection for him to use, but for the $35 fee, and $5 monthly, I love having my device work again.