Thinnest Fiberscope/Borescope to peek between top & bottom pcb

[loop123]

Hi I have a device worth $16500 new and I dont want to open lest it might get damage. It has another pcb on top of the bottom pcb. Im looking for the thinnest but least expensive fiberscope/borescope to peek in between the top and bottom PCBs. Know one?  I just want to know what MCU and amplifier it used. See images below. Thanks.