I went ahead and took the plunge and flashed a new nodeMCU. The replacement works just fine but I hope after a few hours it doesn’t do it again. Afterall, there are only so many extra nodeMCUs and it takes forever to order more. The only thing I can think of is that I left the heatsink off the regulator since it was running off 7.4v battery instead of the normal 12V supply. But the regulator would have been damaged, I would think. It’s a strange one!