Confirmed on the Lite. It works with one transistor directly soldered to the capacitor on the back, but it glitches only with the SDA/SCA lines connected, FW 2.75. This is still with the XIAO, haven put the Waveshare board back yet.
So here is summary of my experiments so far:
-two transistors, one back and one front, no SDA and SCL: glitch
-two transistors, one back and one front, SDA and SCL: glitch
-one transistor on back, SDA and SCL: glitch
-one transistor on back, SDA and SCL: no glitch
-one transistor on front, no SDA and SCL: no glitch
-one transistor on front, SDA and SCL: no glitch
Those were all with the XIAO board, so assuming it needed a second transistor I installed the Waveshare board back and all I got was blinking blue light for few minutes ending with 3 shot yellow blinks 3 times. I believe this means it ran out of attempts.
Back to the XIAO board, but this time I removed the USB port, shield and buttons in preparation for permanent install and what do you know, now the XIAO board is not glitching either. It behaves just like the Waveshere did. What the hell.
Does the heat from disordering the unnecessary parts messes up those board somehow, they seem to be functional?