Unable to program STM32F103 through UART

[Nv7]

I created a custom board with the STM32 (F103C8T6), and I am trying to program it using a FTDI USB to Serial module. However, nothing is happening, it doesn't seem to be sending anything and when I try using STM32CubeProgrammer it says:
Timeout error occured while waiting for acknowledgement.
Error: Activating device: KO. Please, verify the boot mode configuration and check the serial port configuration. Reset your device then try again...

Relevant schematics:

Note that BTEN is unconnected and the BT0 header pin is connected to VCC (which should put it into boot mode).

I have tried reversing RXD and TXD and both 9600 and 115200 baud rate. How can I debug this?

[waclawek.jan]

No, only newer STM32 have this feature. Read AN2606.

JW

[Nv7]

Ok, I soldered BOOT1 to GND, but its still not doing anything. Any ideas on what else it could be?

[Nv7]

I soldered BOOT1 to GND but it is still not responding to anything. Is there anything I can do to debug?

[Tesla DeLorean]

Outside of STM32 Cube Programmer you can use RealTerm, or other similar terminal applications, to send the 0x7F pattern at 9600 8E1  (8-bit, Even Parity, 1 stop bit), the expected response is 0x79. This is a on-shot connection method, where the system tries to compute the baud rate from the bit pattern. If this fails, reset and try again.

If it's non-responsive, it generally points to an electrical or circuit issue.

Normally people also provide a means for SWD/JTAG connectivity to program/debug products.

You might be able to connect via USB, in DFU mode, where the device would come up as a "STM32 BOOT DEVICE" type entity in Windows from the System Memory loader in the STM32F1

A picture might help confirm orientation, and counterfeit devices.