The two pin connector on the back. Newer T-Displays come with a connector/leads.

I just wanted to give an update. I have recreated the problem I was seeing before - this time using the "CapacitiveTouch" example provided by LilyGo on their GITHUB page meaning I can rule out anyting in my code as being a problem.
linked here...

Again, the problem is a follows, when the unit is powered from the USB port, it recognizes all touches on the screen without any problems. When the USB power is removed and the unit is powered by the internal battery it sometimes works and sometimes doesn't recognize the touches on the screen. This makes the T Display S3 Pro unusable for me as a battery powered, portable device.

My question is: Do I have a faulty unit or is there some kind on inherent design problem that effects every one of them?

Thank you!

The flashing red light is the battery charger IC status light.
Your board uses an uncommon, but apparently sophisticated charge IC, so I can only speculate.
The only possible states are OFF, flashing at different rates or ON.
You should learn what the light means through observation.

The other LilyGO boards with different LED indicators do something similar.

-Terry

Do you have a Watch 2020-V3 or an Watch-S3?
Makes some difference.

FYI
https://www.reddit.com/r/LilyGO/comments/13wf9g4/twatch_s3/

On some models the swich is GPIO 0.
Useful as a user input and for entering download mode.

That is a bit of a problem! They are 1.27mm 'half pitch', where 2.54mm is the standard 0.1" U.S. DIP package size.
The LilyGO schematic says 'PZ127-2-15-S'.
Your board also has two Qwiic I2C connectors and supplied ribbons!
All of my projects are I2C, but you can program the four I2C pins on the ribbons to be GPIO for LEDs and switches.
The LilyGO T-Display S3 with soldered headers is a much better board for experimenting and education, IMHO.
https://www.lilygo.cc/products/t-display-s3?variant=42351558590645
-Terry

@juande Well, no! I do not use long range WiFi, soi I have not tried.
See the picture I sent last summer and this one, just now:
opex.jpg
I would try a range test with the resistor in place and an IPEX antenna.
If not satisfactory I would unsolder the resistor as shown and rotate it 90 deg!
cheers -Terry

@karls0n The charge regulator on board, TP4056, is a very good device.
The LilyGO T-Display S3 boots back up in seconds, so it should be shut down when not in use.
I would not leave a charging Li-ion battery unattended for very long, Li-ion are very touchy about re-charging too fast from empty. The TP4056 takes care of that but there are worst-case or extreme situations...
It is designed for a couple 16550 types.
It is intended that the USB supplies the charging current, so the LilyGO T-Display S3 is "ON" while charging, but you could program the LCD to turn off the backlight whilst charging!
-Terry

@ferrari2 I had similar problems with the LilyGO T-Display S3 last year, so I made a GitHub repository here:
https://github.com/teastainGit/LilyGO-T-display-S3-setup-and-examples
Couple things to check:

In my repository (https://github.com/teastainGit/LilyGO-T-display-S3-setup-and-examples ) there is a copy of the 'User_Setup_Select.h' file. It must copied to the TFT_eSPI library folder. It is reset to default every time you allow the Arduino IDE to do an update. If there is no image, copy and replace this file.
(in the future I can show you how to easily edit this file instead of copying.)
Try my Hothead example, designed to be easy to compile and rather instructional to read and understand TFT_eSPI and the LilyGO T-Display S3

Let me know how you make out!
-Terry

@smarttracker Is this your board?
https://www.lilygo.cc/en-ca/products/t-sim-a7670e?_pos=1&_psq=A7670G&_ss=e&_v=1.0&variant=42737494458549
Some are purchased for less cost without GPS. GPS is a added cost option.
Screenshot 2023-11-24 at 11.19.06 PM.png
Sorry if this is not helpful to your situation.
The A7670G is a LTE cellular chip.
-Terry

I bought A7670G with included GPS antenna but have the same errors. What it suppose to work?? What is the reason to advertise that this device supports GPS??