So I've always recommended the Heltec kits as a good entry-level kit but I can't anymore due to issues with the USB->UART chips in them. What I originally chalked up as a mild annoyance has now proven to be a safety concern.
I've had 11 of them total. Of those, two had the USB->UART chip fail within the first week. Everything else still worked, so I was able to repurpose them as "repeaters" and manage them over LoRa. Firmware updates were a brute since I had to crack them open and use an external serial connection, but, still, I was willing to continue recommending them as entry level kits.
Cut to today and that is no longer the case after my everyday carry node decided to self destruct in a way that I am very fortunate wasn't a fire.
I woke up and noticed the charge light was kicking on and off in a weird cadence. Clicked the button to see if it was even running (it was) but the battery was down to 30%. It was also hot. Very hot. It's uptime was only about 5 minutes which was also odd.
So I unplug it and crack open the case. Everything on the board looks normal, so I pull the battery and hook it into USB. As I feared, it didn't enumerate at all. Another one down, I sighed. But then things got worse. As I was holding the board in my hand (still connected over USB), I notice my finger started to get painfully hot. The hot component was the USB-UART chip.
On a hunch, I hooked my USB-C power meter inline with the cable, put it back on the USB charger it normally uses, and lo and behold, it was showing 9V. To rule out the USB charger, I tested it with another one of my Heltecs with a dead UART chip, and it was a steady 5V as expected.
So my best guess is the USB-UART failed in such a way that the data pins triggered the wall charger to go into quick charge mode and destroyed it with an over voltage. I'm genuinely surprised the battery didn't catch on fire as hot as that chip was getting since it was right on top of the battery inside the case.