1.8 V on 3.3V Pin, T-Beam unresponsive

I pulled a t-beam which had become unresponsive today. Blue LED was lit and seemed to be “on”. After cycling power none of the leds come on anymore and the t-beam is unresponsive.
Serial port is detected, but sketches cannot be uploaded.

meshtastic --debug
DEBUG:root:Not logging serial output
DEBUG:root:Connecting to /dev/cu.usbserial-01DCD7CD
DEBUG:root:Sending: want_config_id: 567778367
Traceback (most recent call last):
File “/usr/local/bin/meshtastic”, line 8, in
sys.exit(main())
File “/usr/local/lib/python3.9/site-packages/meshtastic/main.py”, line 622, in main
common()
File “/usr/local/lib/python3.9/site-packages/meshtastic/main.py”, line 470, in common
client = SerialInterface(
File “/usr/local/lib/python3.9/site-packages/meshtastic/init.py”, line 935, in init
StreamInterface.init(
File “/usr/local/lib/python3.9/site-packages/meshtastic/init.py”, line 771, in init
self.connect()
File “/usr/local/lib/python3.9/site-packages/meshtastic/init.py”, line 793, in connect
self._waitConnected()
File “/usr/local/lib/python3.9/site-packages/meshtastic/init.py”, line 422, in _waitConnected
raise Exception(“Timed out waiting for connection completion”)
Exception: Timed out waiting for connection completion

I tried pulling GPIO0 to GND and uploading anew, removing battery etc.

Board looks undamaged and shows 3,3V on Pins 21 & 22, 4.2 V on VIN, but just 1.8V on the 3.3V pin.
5V pin shows 4.2V on battery and 5V when powered via USB.
(also see AXP192 issues).

After some reading I see that there has been a similar case reported on the TTN website (no solution though other than uploading code directly to the AXP192), and on ESP32 Boot Mode I can see that if Pin 12 is somehow driven high, then the flash voltage ends up being 1.8V rather than 3,3 although thats probably not what I am seeing here.

Any suggestion as to how I can unbrick the T-beam and what could have happened?
It had been running for 2 weeks as a solar node without trouble or intervention prior to this.

@Nanovitruvius try connecting 5v and Gnd on the header holes to a 5v regulated supply and see if it comes on. I soldered some wires into the header holes and connected to a lab power supply. That is the only way I could get mine to work. I hope it comes back on for you.

After some further testing, probing etc it seems like there is a bad solder joint somewhere, but couldnt quite figure out where. I suspect it might be one of the esp32 qfn pins. Took a heat-gun to the t-beam, which revived it.
Tested ok, uploaded code and used it for a while, but now the joint seems to have failed again, and the t-beam is dead.
Will retry with fine tip soldering iron, am marking this topic as solved.