I purchased a Mister FPGA with addon boards some time ago, including a 32 MB SDRAM module.
Everything worked fine for months, but suddenly when I loaded the C64 core, I would get gibberish characters on screen (still in the style and colouring of the C64). Other cores that required SDRAM also stopped working, but cores that don't require it work fine. I did some memtests and they failed terribly.
So I bought another SDRAM module, but it fails the memory tests as well, and the C64 shows the exact same gibberish.
Could it be that my de10 nano is broken? Is there a place I can get it fixed if so?