Buttons on steamdeck are falling off

Hello friends, I've encountered a problem with the seback. The joystick buttons periodically fall off. I've replaced the main joystick board, then replaced the ribbon cable, but nothing seems to work. I can't find the main board to understand which chip is responsible for the controller, as I suspect that it's overheating and causing the joysticks to fall off on the motherboard. Please help me find this issue.