See if you can insert a piece of hard plastic in between the boards and press the button that it's in there, both with the board powered up and not. If you don't have a piece of hard plastic you can do it with a flat head screwdriver but be very careful to avoid touching any of the boards or exposed pads with it.
If you have a UART adapter, connect it to the GND and UART0-TX (P1.30) pins and aee if you get any log while powering up the board. If you don't have a UART adapter but you have another Bela, follow instructions here to use the other Bela as a UART adapter: https://learn.bela.io/using-bela/advanced-topics/bela-as-a-uart-adapter/