Re-program STM32F102 trouble

I am trying to make some custom firmware for a MIDI controller (AKAI LPD8). There is an STM32F102R8T6 chip in the unit. I am trying to reach it with a programmer to wipe it, but it seems to not be responsive.

Some information and thing I have tried:

• The firmware that came with the unit works, so the chip is not broken
• Removed the components connected to the programming pins (PA9-PA10 and PA13-PA14)
• I am able to pull BOOT0 high and have it not run the main program, but I am however not able to get a life sign using either an ST-Link2(clone) connected to PA13/14, nor a USB to serial adapter connected to PA9/PA10, so I am not sure what mode it is in
• The connection has been checked, and RX-TX etc is the correct way around (but also for the sake of trying it all, I reversed the connections as well...).
• Tried both the STM32CubeProgrammer and stm32flash, but none connects.

I am actually not sure if AKAI have locked the chip in such a way that you cannot even do a full chip erase and use the chip for something new? The NRST pin is strangely not doing anything to the running of the firmware either when I try to pull it low.

Is there a way to reprogram these chips when they come off of a commercial product, or are they permanently locked?

Any solution/tips?

After hours of trying different ways of making it work (also tried the alternate mapping of the UART port), and probed the TX pin as suggested by Tom V to no avail, I have given up working on that specific chip and ordered an upgrade from the STM32F4 family instead to replace it with. A lot more power and useful peripherals.

A bit of a non-answer to the specific question. Frustrating to not have found out what was wrong (chip or approach) but being mindful of the sunk cost fallacy, I think it was best to just replace the chip with a fresh one and start development from there.