Wifi LoRa 32 v2 5v power Issues

#1

I have killed 3 of these units by applying 5v to the 5v pin. I initially powered up a board this way while assembling everything and had the LED on the board lit and assumed that all was OK. I was developing on another board (powered via USB) and when it came time to test, swapped over the boards (not realizing that although the LED was lit, the CP2102 USB-Serial chip had died). Of course, this immediately killed the second board. My immediate response to this was to try a third board… All 3 boards, regardless of how they are powered (USB/5V/Batt), give no response and have the CP2102 IC heat up too hot to touch.

My last 2 undamaged units work just fine using the exact same 5V supply applied to the USB port via a modified cable.

Anyone have any insight as to what is going on here?

#2

Here is the schematic https://resource.heltec.cn/download/WiFi_LoRa_32/V2/WIFI_LoRa_32_V2(868-915).PDF .
From looking at that the CP2102 it is powered directly from the 5V. Looking at the schematic USB 5V only goes through a fuse so powering it from the 5V pin should not make a difference. Quite a mystery.

Just a bunch of questions that might help figure it out:
Are you sure you had 5V and not over?
What was your 5V source? Power supply? Wall transformer? USB cable with the 5V split out?
Polarity correct?
What pin did you connect to for the 5V?