My friends Uno went in washer. I gave it a week to dry and when i plug it in, it works. But when I shake I hear something shaking around inside it. What do I hear shaking around?
It could be the USB port, barrel jack port, or most likely the pin header. The pin headers are a plastic shell with a two-point prong thing that goes in it. the pin could have desoldered when in the washer. check the pin headers. It might also be the inside of capacitors but that is highly unlikely.