Oops! Select 'Sanguino' in 'Tools > Boards' and 'ATmega644P' or 'ATmega1284P' in 'Tools > Processor

Please help. I only have 1 strand of hair left to pull out.
I’m trying to build firmware - either Marlin 2.0 or bugfix 2.0 (I don’t care which at this point) for my SKR v1.3, and anytime I hit build, I get the above error. Even if I don’t alter anything at all from the source files, I still can’t build. And I have no idea where these “Tools” places are.
I’m dying. Send help.

Hm… that error message sounds like it’s targeted at the Arduino IDE, not PlatformIO, as it’s the Arduino IDE that has a Tools -> Boards menu.

Are you trying to compile this code? As it shouldn’t even be trying to compile for any of the Sanguino boards, but the LPC1768 which your SKR 1.3 uses. The stock Marlin settings are to build for the megaatmega2560 by default, so I’m not sure how you’re getting the Sanguino related errors.

https://github.com/bigtreetech/BIGTREETECH-SKR-V1.3/tree/master/firmware/Marlin-bugfix-2.0.x

If you’re still having trouble, give a link to the code you’re trying to compile, and copy/paste the output of the build log so we can get a better idea as to what’s happening. When you paste it, use triple backticks ``` (next to the 1 key on the number row) before and after the log text so it gets properly formatted.